linux-kernel - [PATCH] tools/perf: use local variable for segment file offset

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Date:	Thu, 2 Oct 2014 15:38:41 +0100
From:	Romeo Cane <romeo.cane.ext@...iant.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>
CC:	Adrian Hunter <adrian.hunter@...el.com>,
	Jiri Olsa <jolsa@...hat.com>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] tools/perf: use local variable for segment file offset

The value of phdr->p_offset is stored inside a buffer that gets reallocated, so it could become corrupted if the new size isn't big enough to contain it

Signed-off-by: Romeo Cane <romeo.cane.ext@...iant.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 c9541fe..bf13e46 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;
+			Elf32_Off tmp_off;
 
 			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;
+			tmp_off = 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, tmp_off, 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;
+			Elf64_Off tmp_off;
 
 			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;
+			tmp_off = 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, tmp_off, SEEK_SET);
 			if (fread(buf, buf_size, 1, fp) != 1)
 				goto out_free;
 
-- 
1.8.3.2

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