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* asan.c: Formatting cleanups.
From-SVN: r193442
This commit is contained in:
Jakub Jelinek
parent
f35db108b9
commit
497a1c6692
@ -1,4 +1,8 @@
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2012-11-12 Wei Mi <wmi@google.com>
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2012-11-12 Jakub Jelinek <jakub@redhat.com>
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* asan.c: Formatting cleanups.
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2012-11-12 Wei Mi <wmi@google.com>
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* gcc.c (LINK_COMMAND_SPEC): Add -lasan to link command if
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-faddress-sanitizer is on.
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@ -28,7 +32,6 @@
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* asan.c (create_cond_insert_point_before_iter): Factorize out of ...
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(build_check_stmt): ... here.
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2012-11-12 Dodji Seketeli <dodji@redhat.com>
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* asan.c (create_cond_insert_point_before_iter): Factorize out of ...
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@ -40,7 +43,7 @@
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represented by an SSA_NAME.
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2012-11-12 Jakub Jelinek <jakub@redhat.com>
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Wei Mi <wmi@google.com>
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Wei Mi <wmi@google.com>
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* varasm.c: Include asan.h.
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(assemble_noswitch_variable): Grow size by asan_red_zone_size
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@ -111,7 +114,7 @@
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2012-11-12 Jakub Jelinek <jakub@redhat.com>
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Xinliang David Li <davidxl@google.com>
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Dodji Seketeli <dodji@redhat.com>
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Dodji Seketeli <dodji@redhat.com>
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* Makefile.in (GTFILES): Add $(srcdir)/asan.c.
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(asan.o): Update the dependencies of asan.o.
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@ -155,9 +158,9 @@
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* config/i386/i386.c (ix86_asan_shadow_offset): New function.
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(TARGET_ASAN_SHADOW_OFFSET): Define.
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2012-11-12 Wei Mi <wmi@google.com>
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Diego Novillo <dnovillo@google.com>
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Dodji Seketeli <dodji@redhat.com>
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2012-11-12 Wei Mi <wmi@google.com>
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Diego Novillo <dnovillo@google.com>
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Dodji Seketeli <dodji@redhat.com>
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* Makefile.in: Add asan.c and its dependencies.
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* common.opt: Add -faddress-sanitizer option.
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177
gcc/asan.c
177
gcc/asan.c
@ -33,42 +33,41 @@ along with GCC; see the file COPYING3. If not see
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#include "optabs.h"
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#include "output.h"
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/*
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AddressSanitizer finds out-of-bounds and use-after-free bugs
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with <2x slowdown on average.
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/* AddressSanitizer finds out-of-bounds and use-after-free bugs
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with <2x slowdown on average.
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The tool consists of two parts:
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instrumentation module (this file) and a run-time library.
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The instrumentation module adds a run-time check before every memory insn.
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For a 8- or 16- byte load accessing address X:
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ShadowAddr = (X >> 3) + Offset
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ShadowValue = *(char*)ShadowAddr; // *(short*) for 16-byte access.
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if (ShadowValue)
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__asan_report_load8(X);
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For a load of N bytes (N=1, 2 or 4) from address X:
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ShadowAddr = (X >> 3) + Offset
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ShadowValue = *(char*)ShadowAddr;
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if (ShadowValue)
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if ((X & 7) + N - 1 > ShadowValue)
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__asan_report_loadN(X);
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Stores are instrumented similarly, but using __asan_report_storeN functions.
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A call too __asan_init() is inserted to the list of module CTORs.
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The tool consists of two parts:
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instrumentation module (this file) and a run-time library.
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The instrumentation module adds a run-time check before every memory insn.
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For a 8- or 16- byte load accessing address X:
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ShadowAddr = (X >> 3) + Offset
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ShadowValue = *(char*)ShadowAddr; // *(short*) for 16-byte access.
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if (ShadowValue)
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__asan_report_load8(X);
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For a load of N bytes (N=1, 2 or 4) from address X:
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ShadowAddr = (X >> 3) + Offset
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ShadowValue = *(char*)ShadowAddr;
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if (ShadowValue)
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if ((X & 7) + N - 1 > ShadowValue)
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__asan_report_loadN(X);
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Stores are instrumented similarly, but using __asan_report_storeN functions.
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A call too __asan_init() is inserted to the list of module CTORs.
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The run-time library redefines malloc (so that redzone are inserted around
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the allocated memory) and free (so that reuse of free-ed memory is delayed),
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provides __asan_report* and __asan_init functions.
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The run-time library redefines malloc (so that redzone are inserted around
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the allocated memory) and free (so that reuse of free-ed memory is delayed),
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provides __asan_report* and __asan_init functions.
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Read more:
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http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
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Read more:
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http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
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The current implementation supports detection of out-of-bounds and
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use-after-free in the heap, on the stack and for global variables.
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The current implementation supports detection of out-of-bounds and
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use-after-free in the heap, on the stack and for global variables.
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[Protection of stack variables]
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[Protection of stack variables]
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To understand how detection of out-of-bounds and use-after-free works
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for stack variables, lets look at this example on x86_64 where the
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stack grows downward:
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To understand how detection of out-of-bounds and use-after-free works
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for stack variables, lets look at this example on x86_64 where the
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stack grows downward:
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int
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foo ()
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@ -82,28 +81,28 @@ along with GCC; see the file COPYING3. If not see
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return a[5] + b[1];
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}
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For this function, the stack protected by asan will be organized as
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follows, from the top of the stack to the bottom:
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For this function, the stack protected by asan will be organized as
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follows, from the top of the stack to the bottom:
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Slot 1/ [red zone of 32 bytes called 'RIGHT RedZone']
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Slot 1/ [red zone of 32 bytes called 'RIGHT RedZone']
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Slot 2/ [8 bytes of red zone, that adds up to the space of 'a' to make
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the next slot be 32 bytes aligned; this one is called Partial
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Redzone; this 32 bytes alignment is an asan constraint]
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Slot 2/ [8 bytes of red zone, that adds up to the space of 'a' to make
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the next slot be 32 bytes aligned; this one is called Partial
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Redzone; this 32 bytes alignment is an asan constraint]
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Slot 3/ [24 bytes for variable 'a']
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Slot 3/ [24 bytes for variable 'a']
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Slot 4/ [red zone of 32 bytes called 'Middle RedZone']
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Slot 4/ [red zone of 32 bytes called 'Middle RedZone']
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Slot 5/ [24 bytes of Partial Red Zone (similar to slot 2]
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Slot 5/ [24 bytes of Partial Red Zone (similar to slot 2]
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Slot 6/ [8 bytes for variable 'b']
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Slot 6/ [8 bytes for variable 'b']
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Slot 7/ [32 bytes of Red Zone at the bottom of the stack, called 'LEFT
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RedZone']
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Slot 7/ [32 bytes of Red Zone at the bottom of the stack, called
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'LEFT RedZone']
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The 32 bytes of LEFT red zone at the bottom of the stack can be
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decomposed as such:
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The 32 bytes of LEFT red zone at the bottom of the stack can be
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decomposed as such:
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1/ The first 8 bytes contain a magical asan number that is always
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0x41B58AB3.
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@ -122,7 +121,7 @@ along with GCC; see the file COPYING3. If not see
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3/ The following 16 bytes of the red zone have no particular
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format.
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The shadow memory for that stack layout is going to look like this:
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The shadow memory for that stack layout is going to look like this:
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- content of shadow memory 8 bytes for slot 7: 0xF1F1F1F1.
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The F1 byte pattern is a magic number called
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@ -149,39 +148,39 @@ along with GCC; see the file COPYING3. If not see
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seat between two 32 aligned slots of {variable,padding}.
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- content of shadow memory 8 bytes for slot 3 and 2:
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0xFFFFFFFFF4000000. This represents is the concatenation of
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0xF4000000. This represents is the concatenation of
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variable 'a' and the partial red zone following it, like what we
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had for variable 'b'. The least significant 3 bytes being 00
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means that the 3 bytes of variable 'a' are addressable.
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- content of shadow memory 8 bytes for slot 1: 0xFFFFFFFFF3F3F3F3.
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- content of shadow memory 8 bytes for slot 1: 0xF3F3F3F3.
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The F3 byte pattern is a magic number called
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ASAN_STACK_MAGIC_RIGHT. It flags the fact that the memory
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region for this shadow byte is a RIGHT red zone intended to seat
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at the top of the variables of the stack.
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Note that the real variable layout is done in expand_used_vars in
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cfgexpand.c. As far as Address Sanitizer is concerned, it lays out
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stack variables as well as the different red zones, emits some
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prologue code to populate the shadow memory as to poison (mark as
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non-accessible) the regions of the red zones and mark the regions of
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stack variables as accessible, and emit some epilogue code to
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un-poison (mark as accessible) the regions of red zones right before
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the function exits.
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Note that the real variable layout is done in expand_used_vars in
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cfgexpand.c. As far as Address Sanitizer is concerned, it lays out
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stack variables as well as the different red zones, emits some
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prologue code to populate the shadow memory as to poison (mark as
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non-accessible) the regions of the red zones and mark the regions of
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stack variables as accessible, and emit some epilogue code to
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un-poison (mark as accessible) the regions of red zones right before
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the function exits.
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[Protection of global variables]
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[Protection of global variables]
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The basic idea is to insert a red zone between two global variables
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and install a constructor function that calls the asan runtime to do
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the populating of the relevant shadow memory regions at load time.
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The basic idea is to insert a red zone between two global variables
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and install a constructor function that calls the asan runtime to do
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the populating of the relevant shadow memory regions at load time.
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So the global variables are laid out as to insert a red zone between
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them. The size of the red zones is so that each variable starts on a
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32 bytes boundary.
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So the global variables are laid out as to insert a red zone between
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them. The size of the red zones is so that each variable starts on a
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32 bytes boundary.
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Then a constructor function is installed so that, for each global
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variable, it calls the runtime asan library function
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__asan_register_globals_with an instance of this type:
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Then a constructor function is installed so that, for each global
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variable, it calls the runtime asan library function
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__asan_register_globals_with an instance of this type:
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struct __asan_global
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{
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@ -202,8 +201,8 @@ along with GCC; see the file COPYING3. If not see
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uptr __has_dynamic_init;
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}
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A destructor function that calls the runtime asan library function
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_asan_unregister_globals is also installed. */
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A destructor function that calls the runtime asan library function
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_asan_unregister_globals is also installed. */
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alias_set_type asan_shadow_set = -1;
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@ -475,7 +474,7 @@ asan_protect_global (tree decl)
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return false;
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#endif
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return true;
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return true;
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}
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/* Construct a function tree for __asan_report_{load,store}{1,2,4,8,16}.
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@ -490,13 +489,13 @@ report_error_func (bool is_store, int size_in_bytes)
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char name[100];
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sprintf (name, "__asan_report_%s%d",
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is_store ? "store" : "load", size_in_bytes);
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is_store ? "store" : "load", size_in_bytes);
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fn_type = build_function_type_list (void_type_node, ptr_type_node, NULL_TREE);
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def = build_fn_decl (name, fn_type);
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TREE_NOTHROW (def) = 1;
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TREE_THIS_VOLATILE (def) = 1; /* Attribute noreturn. Surprise! */
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DECL_ATTRIBUTES (def) = tree_cons (get_identifier ("leaf"),
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NULL, DECL_ATTRIBUTES (def));
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DECL_ATTRIBUTES (def) = tree_cons (get_identifier ("leaf"),
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NULL, DECL_ATTRIBUTES (def));
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DECL_ASSEMBLER_NAME (def);
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return def;
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}
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@ -598,7 +597,7 @@ create_cond_insert_point (gimple_stmt_iterator *iter,
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outcoming edge of the 'then block' -- starts with the statement
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pointed to by ITER.
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COND is the condition of the if.
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COND is the condition of the if.
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If THEN_MORE_LIKELY_P is true, the probability of the edge to the
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'then block' is higher than the probability of the edge to the
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@ -796,7 +795,7 @@ build_check_stmt (location_t location, tree base, gimple_stmt_iterator *iter,
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static void
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instrument_derefs (gimple_stmt_iterator *iter, tree t,
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location_t location, bool is_store)
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location_t location, bool is_store)
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{
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tree type, base;
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HOST_WIDE_INT size_in_bytes;
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@ -864,7 +863,7 @@ instrument_mem_region_access (tree base, tree len,
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if (len != 0)
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{
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//asan instrumentation code goes here.
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}
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}
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// falltrough instructions, starting with *ITER. */
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gimple g = gimple_build_cond (NE_EXPR,
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@ -930,7 +929,7 @@ instrument_mem_region_access (tree base, tree len,
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region_end =
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gimple_build_assign_with_ops (POINTER_PLUS_EXPR,
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make_ssa_name (TREE_TYPE (base), NULL),
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gimple_assign_lhs (region_end),
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gimple_assign_lhs (region_end),
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gimple_assign_lhs (offset));
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gimple_set_location (region_end, location);
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gsi_insert_after (&gsi, region_end, GSI_NEW_STMT);
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@ -1378,7 +1377,7 @@ transform_statements (void)
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{
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if (bb->index >= saved_last_basic_block) continue;
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for (i = gsi_start_bb (bb); !gsi_end_p (i);)
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{
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{
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gimple s = gsi_stmt (i);
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if (gimple_assign_single_p (s))
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@ -1391,7 +1390,7 @@ transform_statements (void)
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continue;
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}
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gsi_next (&i);
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}
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}
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}
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}
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@ -1594,18 +1593,18 @@ struct gimple_opt_pass pass_asan =
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{
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{
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GIMPLE_PASS,
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"asan", /* name */
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OPTGROUP_NONE, /* optinfo_flags */
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gate_asan, /* gate */
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asan_instrument, /* execute */
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NULL, /* sub */
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NULL, /* next */
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0, /* static_pass_number */
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TV_NONE, /* tv_id */
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"asan", /* name */
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OPTGROUP_NONE, /* optinfo_flags */
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gate_asan, /* gate */
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asan_instrument, /* execute */
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NULL, /* sub */
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NULL, /* next */
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0, /* static_pass_number */
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TV_NONE, /* tv_id */
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PROP_ssa | PROP_cfg | PROP_gimple_leh,/* properties_required */
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0, /* properties_provided */
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0, /* properties_destroyed */
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0, /* todo_flags_start */
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0, /* properties_provided */
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0, /* properties_destroyed */
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0, /* todo_flags_start */
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TODO_verify_flow | TODO_verify_stmts
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| TODO_update_ssa /* todo_flags_finish */
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}
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@ -1622,7 +1621,7 @@ struct gimple_opt_pass pass_asan_O0 =
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{
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GIMPLE_PASS,
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"asan0", /* name */
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OPTGROUP_NONE, /* optinfo_flags */
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OPTGROUP_NONE, /* optinfo_flags */
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gate_asan_O0, /* gate */
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asan_instrument, /* execute */
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NULL, /* sub */
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