2012-08-13 18:38:21

by Arnaldo Carvalho de Melo

[permalink] [raw]
Subject: [PATCH 30/38] perf symbols: Avoid segfault in elf_strptr

From: Cody P Schafer <[email protected]>

If we call elf_section_by_name() with a truncated elf image (ie: the
file header indicates that the section headers are placed past the end
of the file), elf_strptr() causes a segfault within libelf.

Avoid this by checking that we can access the section string table
properly.

Should really be fixed in libelf/elfutils.

Signed-off-by: Cody P Schafer <[email protected]>
Cc: David Hansen <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Matt Hellsley <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Sukadev Bhattiprolu <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
tools/perf/util/symbol-elf.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index a2e994e..a9a194d 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -129,6 +129,10 @@ static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
Elf_Scn *sec = NULL;
size_t cnt = 1;

+ /* Elf is corrupted/truncated, avoid calling elf_strptr. */
+ if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL))
+ return NULL;
+
while ((sec = elf_nextscn(elf, sec)) != NULL) {
char *str;

--
1.7.1