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c, analyzer: fix ICE with -fanalyzer and -Wunused-macros [PR107711]

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PR analyzer/107711 reports an ICE since r13-4073-gd8aba860b34203 with
the combination of -fanalyzer and -Wunused-macros.

The issue is that in c_translation_unit::consider_macro's call to
cpp_create_reader I was passing "ident_hash" for use by the the new
reader, but that takes ownership of that hash_table, so that ident_hash
erroneously gets freed when c_translation_unit::consider_macro calls
cpp_destroy, leading to a use-after-free in -Wunused-macros, where:

(gdb) p pfile->hash_table->pfile == pfile
$23 = false

and it's instead pointing at the freed reader from consider_macro,
leading to a use-after-free ICE.

Fixed thusly.

gcc/c/ChangeLog:
	PR analyzer/107711
	* c-parser.cc (ana::c_translation_unit::consider_macro): Pass NULL
	to cpp_create_reader, rather than ident_hash, so that the new
	reader gets its own hash table.

gcc/testsuite/ChangeLog:
	PR analyzer/107711
	* gcc.dg/analyzer/named-constants-Wunused-macros.c: New test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>
This commit is contained in:
David Malcolm 2022-11-17 12:34:56 -05:00
parent 0045d254c0
commit f9ed1d24ee
2 changed files with 20 additions and 1 deletions
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2
gcc/c/c-parser.cc
View File

@ -1717,7 +1717,7 @@ private:
return NULL_TREE;
cpp_reader *old_parse_in = parse_in;
parse_in = cpp_create_reader (CLK_GNUC89, ident_hash, line_table);
parse_in = cpp_create_reader (CLK_GNUC89, NULL, line_table);
pretty_printer pp;
pp_string (&pp, (const char *) tok.val.str.text);

19
gcc/testsuite/gcc.dg/analyzer/named-constants-Wunused-macros.c Normal file
View File

@ -0,0 +1,19 @@
/* Regression test for interaction of named constants in -fanalyzer with
-Wunused-macros (PR analyzer/107711). */
/* { dg-additional-options "-Wunused-macros" } */
#include "analyzer-decls.h"
/* Various constants used by the fd state machine. */
#define O_ACCMODE 42 /* { dg-warning "-: macro \"O_ACCMODE\" is not used" } */
#define O_RDONLY 0x1 /* { dg-warning "-: macro \"O_RDONLY\" is not used" } */
#define O_WRONLY 010 /* { dg-warning "-: macro \"O_WRONLY\" is not used" } */
void test_sm_fd_constants (void)
{
__analyzer_dump_named_constant ("O_ACCMODE"); /* { dg-warning "named constant 'O_ACCMODE' has value '42'" } */
__analyzer_dump_named_constant ("O_RDONLY"); /* { dg-warning "named constant 'O_RDONLY' has value '1'" } */
__analyzer_dump_named_constant ("O_WRONLY"); /* { dg-warning "named constant 'O_WRONLY' has value '8'" } */
}