linux-kernel - [tip:perf/urgent] perf symbols: Fix use after free in filename__read_build

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Message-ID: <tip-7ad74b41e56e4f7f42c6b765bc44428cd09310d7@git.kernel.org>
Date:	Wed, 17 Dec 2014 22:33:18 -0800
From:	tip-bot for Mitchell Krome <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mingo@...hat.com, tglx@...utronix.de, mitchellkrome@...il.com,
	jolsa@...hat.com, paulus@...ba.org, mingo@...nel.org,
	hpa@...or.com, acme@...hat.com, linux-kernel@...r.kernel.org,
	jolsa@...nel.org, a.p.zijlstra@...llo.nl
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@...il.com>
AuthorDate: Tue, 16 Dec 2014 12:16:12 +1000
Committer:  Arnaldo Carvalho de Melo <acme@...hat.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@...il.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Link: http://lkml.kernel.org/r/20141216021612.GA7199@mitchell
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.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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