[compiler-rt] 83ac182 - Hwasan reporting check for dladdr failing

[Matthew Malcomson via llvm-commits]

Author: Matthew Malcomson
Date: 2020-11-16T12:25:27Z
New Revision: 83ac18205ec69a00ac2be3b603bc3a61293fbe89

URL: https://github.com/llvm/llvm-project/commit/83ac18205ec69a00ac2be3b603bc3a61293fbe89
DIFF: https://github.com/llvm/llvm-project/commit/83ac18205ec69a00ac2be3b603bc3a61293fbe89.diff

LOG: Hwasan reporting check for dladdr failing

In `GetGlobalSizeFromDescriptor` we use `dladdr` to get info on the the
current address.  `dladdr` returns 0 if it failed.
During testing on Linux this returned 0 to indicate failure, and
populated the `info` structure with a NULL pointer which was
dereferenced later.

This patch checks for `dladdr` returning 0, and in that case returns 0
from `GetGlobalSizeFromDescriptor` to indicate failure of identifying
the address.

This occurs when `GetModuleNameAndOffsetForPC` succeeds for some address
not in a dynamically loaded library.  One example is when the found
"module" is '[stack]' having come from parsing /proc/self/maps.

Differential Revision: https://reviews.llvm.org/D91344

Added: 
    

Modified: 
    compiler-rt/lib/hwasan/hwasan_report.cpp

Removed: 
    


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diff  --git a/compiler-rt/lib/hwasan/hwasan_report.cpp b/compiler-rt/lib/hwasan/hwasan_report.cpp
index 0be7deeaee1a..894a149775f2 100644
--- a/compiler-rt/lib/hwasan/hwasan_report.cpp
+++ b/compiler-rt/lib/hwasan/hwasan_report.cpp
@@ -254,7 +254,8 @@ static bool TagsEqual(tag_t tag, tag_t *tag_ptr) {
 static uptr GetGlobalSizeFromDescriptor(uptr ptr) {
   // Find the ELF object that this global resides in.
   Dl_info info;
-  dladdr(reinterpret_cast<void *>(ptr), &info);
+  if (dladdr(reinterpret_cast<void *>(ptr), &info) == 0)
+    return 0;
   auto *ehdr = reinterpret_cast<const ElfW(Ehdr) *>(info.dli_fbase);
   auto *phdr_begin = reinterpret_cast<const ElfW(Phdr) *>(
       reinterpret_cast<const u8 *>(ehdr) + ehdr->e_phoff);