From: Matthew Malcomson <matthew.malcomson@arm.com>
Date: Wed, 25 Nov 2020 16:31:35 +0000 (+0000)
Subject: libsanitizer: Hwasan reporting check for dladdr failing
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=8eb12742e8ae5a16e05be627c701234dc7c13504;p=gcc.git

libsanitizer: 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.

Cherry-pick from 83ac18205ec69a00ac2be3b603bc3a61293fbe89.

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

diff --git a/libsanitizer/hwasan/hwasan_report.cpp b/libsanitizer/hwasan/hwasan_report.cpp
index 0be7deeaee1..894a149775f 100644
--- a/libsanitizer/hwasan/hwasan_report.cpp
+++ b/libsanitizer/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);