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Subject[tip:perf/urgent] perf symbols: Fix use after free in filename__read_build_id
Commit-ID:  7ad74b41e56e4f7f42c6b765bc44428cd09310d7
Gitweb: http://git.kernel.org/tip/7ad74b41e56e4f7f42c6b765bc44428cd09310d7
Author: Mitchell Krome <mitchellkrome@gmail.com>
AuthorDate: Tue, 16 Dec 2014 12:16:12 +1000
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Wed, 17 Dec 2014 11:58:17 -0300

perf symbols: Fix use after free in filename__read_build_id

In filename__read_build_id, phdr points to memory in buf, which gets realloced
before a call to fseek that uses phdr->p_offset. This change stores the value
of p_offset before buf is realloced, so the fseek can use the value safely.

Signed-off-by: Mitchell Krome <mitchellkrome@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20141216021612.GA7199@mitchell
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/symbol-minimal.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c
index fa585c6..d7efb03 100644
--- a/tools/perf/util/symbol-minimal.c
+++ b/tools/perf/util/symbol-minimal.c
@@ -129,6 +129,7 @@ int filename__read_build_id(const char *filename, void *bf, size_t size)

for (i = 0, phdr = buf; i < ehdr.e_phnum; i++, phdr++) {
void *tmp;
+ long offset;

if (need_swap) {
phdr->p_type = bswap_32(phdr->p_type);
@@ -140,12 +141,13 @@ int filename__read_build_id(const char *filename, void *bf, size_t size)
continue;

buf_size = phdr->p_filesz;
+ offset = phdr->p_offset;
tmp = realloc(buf, buf_size);
if (tmp == NULL)
goto out_free;

buf = tmp;
- fseek(fp, phdr->p_offset, SEEK_SET);
+ fseek(fp, offset, SEEK_SET);
if (fread(buf, buf_size, 1, fp) != 1)
goto out_free;

@@ -178,6 +180,7 @@ int filename__read_build_id(const char *filename, void *bf, size_t size)

for (i = 0, phdr = buf; i < ehdr.e_phnum; i++, phdr++) {
void *tmp;
+ long offset;

if (need_swap) {
phdr->p_type = bswap_32(phdr->p_type);
@@ -189,12 +192,13 @@ int filename__read_build_id(const char *filename, void *bf, size_t size)
continue;

buf_size = phdr->p_filesz;
+ offset = phdr->p_offset;
tmp = realloc(buf, buf_size);
if (tmp == NULL)
goto out_free;

buf = tmp;
- fseek(fp, phdr->p_offset, SEEK_SET);
+ fseek(fp, offset, SEEK_SET);
if (fread(buf, buf_size, 1, fp) != 1)
goto out_free;


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