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Message-ID: <20250501070003.22251-1-irogers@google.com>
Date: Thu, 1 May 2025 00:00:03 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>,
Kan Liang <kan.liang@...ux.intel.com>, linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v1] perf symbol-minimal: Fix double free in filename__read_build_id
Running the "perf script task-analyzer tests" with address sanitizer
showed a double free:
```
FAIL: "test_csv_extended_times" Error message: "Failed to find required string:'Out-Out;'."
=================================================================
==19190==ERROR: AddressSanitizer: attempting double-free on 0x50b000017b10 in thread T0:
#0 0x55da9601c78a in free (perf+0x26078a) (BuildId: e7ef50e08970f017a96fde6101c5e2491acc674a)
#1 0x55da96640c63 in filename__read_build_id tools/perf/util/symbol-minimal.c:221:2
0x50b000017b10 is located 0 bytes inside of 112-byte region [0x50b000017b10,0x50b000017b80)
freed by thread T0 here:
#0 0x55da9601ce40 in realloc (perf+0x260e40) (BuildId: e7ef50e08970f017a96fde6101c5e2491acc674a)
#1 0x55da96640ad6 in filename__read_build_id tools/perf/util/symbol-minimal.c:204:10
previously allocated by thread T0 here:
#0 0x55da9601ca23 in malloc (perf+0x260a23) (BuildId: e7ef50e08970f017a96fde6101c5e2491acc674a)
#1 0x55da966407e7 in filename__read_build_id tools/perf/util/symbol-minimal.c:181:9
SUMMARY: AddressSanitizer: double-free (perf+0x26078a) (BuildId: e7ef50e08970f017a96fde6101c5e2491acc674a) in free
==19190==ABORTING
FAIL: "invocation of perf script report task-analyzer --csv-summary csvsummary --summary-extended command failed" Error message: ""
FAIL: "test_csvsummary_extended" Error message: "Failed to find required string:'Out-Out;'."
---- end(-1) ----
132: perf script task-analyzer tests : FAILED!
```
The buf_size if always set to phdr->p_filesz, but that may be 0
causing a free and realloc to return NULL. This is treated in
filename__read_build_id like a failure and the buffer is freed again.
To avoid this problem only grow buf, meaning the buf_size will never
be 0. This also reduces the number of memory (re)allocations.
Fixes: b691f64360ec ("perf symbols: Implement poor man's ELF parser")
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
tools/perf/util/symbol-minimal.c | 34 +++++++++++++++++---------------
1 file changed, 18 insertions(+), 16 deletions(-)
diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c
index c6f369b5d893..d8da3da01fe6 100644
--- a/tools/perf/util/symbol-minimal.c
+++ b/tools/perf/util/symbol-minimal.c
@@ -147,18 +147,19 @@ int filename__read_build_id(const char *filename, struct build_id *bid)
if (phdr->p_type != PT_NOTE)
continue;
- buf_size = phdr->p_filesz;
offset = phdr->p_offset;
- tmp = realloc(buf, buf_size);
- if (tmp == NULL)
- goto out_free;
-
- buf = tmp;
+ if (phdr->p_filesz > buf_size) {
+ buf_size = phdr->p_filesz;
+ tmp = realloc(buf, buf_size);
+ if (tmp == NULL)
+ goto out_free;
+ buf = tmp;
+ }
fseek(fp, offset, SEEK_SET);
- if (fread(buf, buf_size, 1, fp) != 1)
+ if (fread(buf, phdr->p_filesz, 1, fp) != 1)
goto out_free;
- ret = read_build_id(buf, buf_size, bid, need_swap);
+ ret = read_build_id(buf, phdr->p_filesz, bid, need_swap);
if (ret == 0) {
ret = bid->size;
break;
@@ -199,18 +200,19 @@ int filename__read_build_id(const char *filename, struct build_id *bid)
if (phdr->p_type != PT_NOTE)
continue;
- buf_size = phdr->p_filesz;
offset = phdr->p_offset;
- tmp = realloc(buf, buf_size);
- if (tmp == NULL)
- goto out_free;
-
- buf = tmp;
+ if (phdr->p_filesz > buf_size) {
+ buf_size = phdr->p_filesz;
+ tmp = realloc(buf, buf_size);
+ if (tmp == NULL)
+ goto out_free;
+ buf = tmp;
+ }
fseek(fp, offset, SEEK_SET);
- if (fread(buf, buf_size, 1, fp) != 1)
+ if (fread(buf, phdr->p_filesz, 1, fp) != 1)
goto out_free;
- ret = read_build_id(buf, buf_size, bid, need_swap);
+ ret = read_build_id(buf, phdr->p_filesz, bid, need_swap);
if (ret == 0) {
ret = bid->size;
break;
--
2.49.0.967.g6a0df3ecc3-goog
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