https://bugs.kde.org/show_bug.cgi?id=393062
Bug ID: 393062
Summary: Reading build-id ELF note through phdrs triggers
"debuginfo reader: ensure_valid failed"
Product: valgrind
Version: unspecified
Platform: Other
URL: https://bugzilla.redhat.com/show_bug.cgi?id=1566639
OS: Linux
Status: UNCONFIRMED
Severity: normal
Priority: NOR
Component: general
Assignee: jsew...@acm.org
Reporter: m...@klomp.org
Target Milestone: ---
Reported against the Fedora valgrind package.
valgrind /usr/bin/Xvfb :10
==7018== Memcheck, a memory error detector
==7018== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==7018== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==7018== Command: ./build/hw/vfb/Xvfb :10
==7018==
==7018== Valgrind: debuginfo reader: ensure_valid failed:
==7018== Valgrind: during call to ML_(img_get)
==7018== Valgrind: request for range [460632, +12) exceeds
==7018== Valgrind: valid image size of 333064 for image:
==7018== Valgrind:
"/usr/lib/debug/.build-id/3e/30f2307639da3a66b4c72c310049c659461253.debug"
==7018==
==7018== Valgrind: debuginfo reader: Possibly corrupted debuginfo file.
==7018== Valgrind: I can't recover. Giving up. Sorry.
==7018==
The issue is triggered when trying to read the build-id from a .debug file
through the phdrs. The phdrs in a .debug file might not be valid (they are a
copy of the main ELF file) and so even if a build-id is found it might be
invalid (but we might not know). We really shouldn't even try.
This patch fixes the issue:
diff --git a/coregrind/m_debuginfo/readelf.c b/coregrind/m_debuginfo/readelf.c
index 70c28e629..8bd3e049c 100644
--- a/coregrind/m_debuginfo/readelf.c
+++ b/coregrind/m_debuginfo/readelf.c
@@ -1137,7 +1137,11 @@ HChar* find_buildid(DiImage* img, Bool rel_ok, Bool
search_shdrs)
ElfXX_Ehdr ehdr;
ML_(img_get)(&ehdr, img, 0, sizeof(ehdr));
- for (i = 0; i < ehdr.e_phnum; i++) {
+ /* Skip the phdrs when we have to search the shdrs. In separate
+ .debug files the phdrs might not be valid (they are a copy of
+ the main ELF file) and might trigger assertions when getting
+ image notes based on them. */
+ for (i = 0; !search_shdrs && i < ehdr.e_phnum; i++) {
ElfXX_Phdr phdr;
ML_(img_get)(&phdr, img,
ehdr.e_phoff + i * ehdr.e_phentsize, sizeof(phdr));
--
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