Hello. While reading and trying to understand sanopt code, I've noticed that we can possibly optimize out a ASAN_CHECK when there's a BB in between DOM(BB) and BB which can call a freeing function.
Ready to be installed after it survives regression tests? Martin
>From d8ed43c1f8e29cfe63ebd7c40a76715c9c644522 Mon Sep 17 00:00:00 2001 From: marxin <mli...@suse.cz> Date: Tue, 25 Oct 2016 13:29:47 +0200 Subject: [PATCH] Fix not caught use-after-scope with -O1 (PR sanitize/78106) gcc/ChangeLog: 2016-10-25 Martin Liska <mli...@suse.cz> PR sanitizer/78106 * sanopt.c (imm_dom_path_with_freeing_call): Handle gasm statements as they can also contain possibly a freeing call. gcc/testsuite/ChangeLog: 2016-10-25 Martin Liska <mli...@suse.cz> PR sanitizer/78106 * gcc.dg/asan/pr78106.c: New test. --- gcc/sanopt.c | 6 +++++- gcc/testsuite/gcc.dg/asan/pr78106.c | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/asan/pr78106.c diff --git a/gcc/sanopt.c b/gcc/sanopt.c index 27c43da..8a6fbe9 100644 --- a/gcc/sanopt.c +++ b/gcc/sanopt.c @@ -211,8 +211,12 @@ imm_dom_path_with_freeing_call (basic_block bb, basic_block dom) for (gsi = gsi_start_bb (e->src); !gsi_end_p (gsi); gsi_next (&gsi)) { gimple *stmt = gsi_stmt (gsi); + gasm *asm_stmt; - if (is_gimple_call (stmt) && !nonfreeing_call_p (stmt)) + if ((is_gimple_call (stmt) && !nonfreeing_call_p (stmt)) + || ((asm_stmt = dyn_cast <gasm *> (stmt)) + && (gimple_asm_clobbers_memory_p (asm_stmt) + || gimple_asm_volatile_p (asm_stmt)))) { pred_info->has_freeing_call_p = true; break; diff --git a/gcc/testsuite/gcc.dg/asan/pr78106.c b/gcc/testsuite/gcc.dg/asan/pr78106.c new file mode 100644 index 0000000..7c0e05e --- /dev/null +++ b/gcc/testsuite/gcc.dg/asan/pr78106.c @@ -0,0 +1,34 @@ +/* PR sanitizer/78106 */ +/* { dg-do run } */ +/* { dg-options "-fsanitize=address" } */ +/* { dg-shouldfail "asan" } */ + +int *variable; + +void __attribute__((used)) release() +{ + __builtin_free (variable); +} + +int main2(int argc) +{ + *variable = 2; + + if (argc <= 5) + asm volatile ("call release"); + + *variable = 2; + __builtin_abort (); + + return 0; +} + +int main(int argc, char **argv) +{ + variable = __builtin_malloc (sizeof(int)); + return main2(argc); +} + +/* { dg-output "ERROR: AddressSanitizer:? heap-use-after-free on address.*(\n|\r\n|\r)" } */ +/* { dg-output "WRITE of size 4 at.*" } */ +/* { dg-output " #0 0x\[0-9a-f\]+ +in _*main2 .*" } */ -- 2.10.1