<div style="font-family: arial, helvetica, sans-serif; font-size: 10pt">This fix is completely wrong: FakeStack::AddrIsInFakeStack(addr)<div>doesn't return a fake stack frame containing "addr", but a pointer to</div>
<div>a mapped memory region containing a bunch of fake stack frames of the same size.<div><br><div class="gmail_quote">On Thu, Nov 15, 2012 at 7:45 PM, Kostya Serebryany <span dir="ltr"><<a href="mailto:kcc@google.com" target="_blank">kcc@google.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="font-family:arial,helvetica,sans-serif;font-size:10pt">Thanks! <div><div class="h5"><br><br><div class="gmail_quote">
On Thu, Nov 15, 2012 at 7:24 AM, Alexander Potapenko <span dir="ltr"><<a href="mailto:glider@google.com" target="_blank">glider@google.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: glider<br>
Date: Thu Nov 15 09:24:42 2012<br>
New Revision: <a href="tel:168046" value="+49168046" target="_blank">168046</a><br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=168046&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=168046&view=rev</a><br>
Log:<br>
[ASan] Revert r168040 and r168043 and take a cleaner solution suggested by Kostya: return the known frame name for fake stack instead of looking it up.<br>
<br>
Modified:<br>
compiler-rt/trunk/lib/asan/asan_allocator.cc<br>
compiler-rt/trunk/lib/asan/asan_internal.h<br>
compiler-rt/trunk/lib/asan/asan_report.cc<br>
compiler-rt/trunk/lib/asan/asan_thread.cc<br>
<br>
Modified: compiler-rt/trunk/lib/asan/asan_allocator.cc<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_allocator.cc?rev=168046&r1=168045&r2=168046&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_allocator.cc?rev=168046&r1=168045&r2=168046&view=diff</a><br>
==============================================================================<br>
--- compiler-rt/trunk/lib/asan/asan_allocator.cc (original)<br>
+++ compiler-rt/trunk/lib/asan/asan_allocator.cc Thu Nov 15 09:24:42 2012<br>
@@ -998,10 +998,6 @@<br>
CHECK(fake_frame->descr != 0);<br>
CHECK(fake_frame->size_minus_one == size - 1);<br>
PoisonShadow(ptr, size, kAsanStackAfterReturnMagic);<br>
- CHECK(size >= SHADOW_GRANULARITY);<br>
- // Poison the leftmost shadow byte with a special value so that we can find<br>
- // the beginning of the fake frame when reporting an error.<br>
- PoisonShadow(ptr, SHADOW_GRANULARITY, kAsanStackAfterReturnLeftMagic);<br>
}<br>
<br>
} // namespace __asan<br>
<br>
Modified: compiler-rt/trunk/lib/asan/asan_internal.h<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_internal.h?rev=168046&r1=168045&r2=168046&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_internal.h?rev=168046&r1=168045&r2=168046&view=diff</a><br>
==============================================================================<br>
--- compiler-rt/trunk/lib/asan/asan_internal.h (original)<br>
+++ compiler-rt/trunk/lib/asan/asan_internal.h Thu Nov 15 09:24:42 2012<br>
@@ -160,7 +160,6 @@<br>
const int kAsanStackAfterReturnMagic = 0xf5;<br>
const int kAsanInitializationOrderMagic = 0xf6;<br>
const int kAsanUserPoisonedMemoryMagic = 0xf7;<br>
-const int kAsanStackAfterReturnLeftMagic = 0xf8;<br>
const int kAsanGlobalRedzoneMagic = 0xf9;<br>
const int kAsanInternalHeapMagic = 0xfe;<br>
<br>
<br>
Modified: compiler-rt/trunk/lib/asan/asan_report.cc<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_report.cc?rev=168046&r1=168045&r2=168046&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_report.cc?rev=168046&r1=168045&r2=168046&view=diff</a><br>
==============================================================================<br>
--- compiler-rt/trunk/lib/asan/asan_report.cc (original)<br>
+++ compiler-rt/trunk/lib/asan/asan_report.cc Thu Nov 15 09:24:42 2012<br>
@@ -450,7 +450,6 @@<br>
bug_descr = "stack-buffer-overflow";<br>
break;<br>
case kAsanStackAfterReturnMagic:<br>
- case kAsanStackAfterReturnLeftMagic:<br>
bug_descr = "stack-use-after-return";<br>
break;<br>
case kAsanUserPoisonedMemoryMagic:<br>
<br>
Modified: compiler-rt/trunk/lib/asan/asan_thread.cc<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_thread.cc?rev=168046&r1=168045&r2=168046&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_thread.cc?rev=168046&r1=168045&r2=168046&view=diff</a><br>
==============================================================================<br>
--- compiler-rt/trunk/lib/asan/asan_thread.cc (original)<br>
+++ compiler-rt/trunk/lib/asan/asan_thread.cc Thu Nov 15 09:24:42 2012<br>
@@ -118,41 +118,35 @@<br>
<br>
const char *AsanThread::GetFrameNameByAddr(uptr addr, uptr *offset) {<br>
uptr bottom = 0;<br>
- bool is_fake_stack = false;<br>
if (AddrIsInStack(addr)) {<br>
bottom = stack_bottom();<br>
} else {<br>
bottom = fake_stack().AddrIsInFakeStack(addr);<br>
CHECK(bottom);<br>
- is_fake_stack = true;<br>
+ *offset = addr - bottom;<br>
+ return (const char *)((uptr*)bottom)[1];<br>
}<br>
uptr aligned_addr = addr & ~(__WORDSIZE/8 - 1); // align addr.<br>
u8 *shadow_ptr = (u8*)MemToShadow(aligned_addr);<br>
u8 *shadow_bottom = (u8*)MemToShadow(bottom);<br>
<br>
while (shadow_ptr >= shadow_bottom &&<br>
- *shadow_ptr != kAsanStackLeftRedzoneMagic &&<br>
- *shadow_ptr != kAsanStackAfterReturnLeftMagic) {<br>
+ *shadow_ptr != kAsanStackLeftRedzoneMagic) {<br>
shadow_ptr--;<br>
}<br>
<br>
while (shadow_ptr >= shadow_bottom &&<br>
- (*shadow_ptr == kAsanStackLeftRedzoneMagic ||<br>
- *shadow_ptr == kAsanStackAfterReturnLeftMagic)) {<br>
+ *shadow_ptr == kAsanStackLeftRedzoneMagic) {<br>
shadow_ptr--;<br>
}<br>
<br>
if (shadow_ptr < shadow_bottom) {<br>
- // If we're one byte below the fake stack bottom, we've found the frame.<br>
- if (!is_fake_stack || (*shadow_bottom != kAsanStackAfterReturnLeftMagic)) {<br>
- *offset = 0;<br>
- return "UNKNOWN";<br>
- }<br>
+ *offset = 0;<br>
+ return "UNKNOWN";<br>
}<br>
<br>
uptr* ptr = (uptr*)SHADOW_TO_MEM((uptr)(shadow_ptr + 1));<br>
- CHECK((ptr[0] == kCurrentStackFrameMagic) ||<br>
- (is_fake_stack && ptr[0] == kRetiredStackFrameMagic));<br>
+ CHECK(ptr[0] == kCurrentStackFrameMagic);<br>
*offset = addr - (uptr)ptr;<br>
return (const char*)ptr[1];<br>
}<br>
<br>
<br>
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</blockquote></div><br></div></div></div>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div>Alexey Samsonov, MSK</div><br>
</div></div></div>