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d61ef7352b
The function _dl_addr_inside_object is simplified by removing the conditional 'reladdr - l->l_phdr[n].p_vaddr >= 0' which is always true. The function is refactored into it's own object file and a unit test added to verify the correct behaviour of the function.
76 lines
2.5 KiB
C
76 lines
2.5 KiB
C
/* Determine if address is inside object load segments.
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Copyright (C) 1996-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <link.h>
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#include <elf.h>
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/* Return non-zero if ADDR lies within one of L's loadable segments.
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We have three cases we care about.
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Case 1: addr is above a segment.
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+==================+<- l_map_end
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| |<- addr
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|------------------|<- l_addr + p_vaddr + p_memsz
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| |
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|------------------|<- l_addr + p_vaddr
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|------------------|<- l_addr
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| |
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+==================+<- l_map_start
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Case 2: addr is within a segments.
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+==================+<- l_map_end
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| |
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|------------------|<- l_addr + p_vaddr + p_memsz
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| |<- addr
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| |
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|------------------|<- l_addr + p_vaddr
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|------------------|<- l_addr
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| |
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+==================+<- l_map_start
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Case 3: addr is below a segments.
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+==================+<- l_map_end
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| |
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|------------------|<- l_addr + p_vaddr + p_memsz
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| |
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|------------------|<- l_addr + p_vaddr
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|------------------|<- l_addr
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| |<- addr
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+==================+<- l_map_start
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All the arithmetic is unsigned and we shift all the values down by
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l_addr + p_vaddr and then compare the normalized addr to the range
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of interest i.e. 0 <= addr < p_memsz.
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*/
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int
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internal_function
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_dl_addr_inside_object (struct link_map *l, const ElfW(Addr) addr)
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{
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int n = l->l_phnum;
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const ElfW(Addr) reladdr = addr - l->l_addr;
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while (--n >= 0)
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if (l->l_phdr[n].p_type == PT_LOAD
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&& reladdr - l->l_phdr[n].p_vaddr < l->l_phdr[n].p_memsz)
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return 1;
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return 0;
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}
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