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| author | Jakub Jelinek <jakub@redhat.com> | 2018-04-17 22:22:50 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@gcc.gnu.org> | 2018-04-17 22:22:50 +0200 |
| commit | 7504c3bf61443f9255b0a0caf310b5300b59b92d (patch) | |
| tree | 939b6b49b4bfab6a1d9f681469b8ac2b360bfc9f /gcc/asan.c | |
| parent | aa4ec2cdff98cdeec085fa14af4267a51e4e1052 (diff) | |
| download | gcc-7504c3bf61443f9255b0a0caf310b5300b59b92d.zip gcc-7504c3bf61443f9255b0a0caf310b5300b59b92d.tar.gz gcc-7504c3bf61443f9255b0a0caf310b5300b59b92d.tar.bz2 | |
re PR sanitizer/85230 (asan: false positives in kernel on allocas)
PR sanitizer/85230
* asan.c (handle_builtin_stack_restore): Adjust comment. Emit
__asan_allocas_unpoison call and last_alloca_addr = new_sp before
__builtin_stack_restore rather than after it.
* builtins.c (expand_asan_emit_allocas_unpoison): Pass
arg1 + (virtual_dynamic_stack_rtx - stack_pointer_rtx) as second
argument instead of virtual_dynamic_stack_rtx.
From-SVN: r259446
Diffstat (limited to 'gcc/asan.c')
| -rw-r--r-- | gcc/asan.c | 13 |
1 files changed, 6 insertions, 7 deletions
@@ -554,14 +554,14 @@ get_last_alloca_addr () return last_alloca_addr; } -/* Insert __asan_allocas_unpoison (top, bottom) call after +/* Insert __asan_allocas_unpoison (top, bottom) call before __builtin_stack_restore (new_sp) call. The pseudocode of this routine should look like this: - __builtin_stack_restore (new_sp); top = last_alloca_addr; bot = new_sp; __asan_allocas_unpoison (top, bot); last_alloca_addr = new_sp; + __builtin_stack_restore (new_sp); In general, we can't use new_sp as bot parameter because on some architectures SP has non zero offset from dynamic stack area. Moreover, on some architectures this offset (STACK_DYNAMIC_OFFSET) becomes known for each @@ -570,9 +570,8 @@ get_last_alloca_addr () http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi.html#DYNAM-STACK. To overcome the issue we use following trick: pass new_sp as a second parameter to __asan_allocas_unpoison and rewrite it during expansion with - virtual_dynamic_stack_rtx later in expand_asan_emit_allocas_unpoison - function. -*/ + new_sp + (virtual_dynamic_stack_rtx - sp) later in + expand_asan_emit_allocas_unpoison function. */ static void handle_builtin_stack_restore (gcall *call, gimple_stmt_iterator *iter) @@ -584,9 +583,9 @@ handle_builtin_stack_restore (gcall *call, gimple_stmt_iterator *iter) tree restored_stack = gimple_call_arg (call, 0); tree fn = builtin_decl_implicit (BUILT_IN_ASAN_ALLOCAS_UNPOISON); gimple *g = gimple_build_call (fn, 2, last_alloca, restored_stack); - gsi_insert_after (iter, g, GSI_NEW_STMT); + gsi_insert_before (iter, g, GSI_SAME_STMT); g = gimple_build_assign (last_alloca, restored_stack); - gsi_insert_after (iter, g, GSI_NEW_STMT); + gsi_insert_before (iter, g, GSI_SAME_STMT); } /* Deploy and poison redzones around __builtin_alloca call. To do this, we |