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Message-ID: <20221229124728.66515-1-yangjihong1@huawei.com>
Date: Thu, 29 Dec 2022 12:47:28 +0000
From: Yang Jihong <yangjihong1@...wei.com>
To: <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
<mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
<jolsa@...nel.org>, <namhyung@...nel.org>,
<jiwei.sun@...driver.com>, <linux-perf-users@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
CC: <yangjihong1@...wei.com>
Subject: [PATCH v2] perf record: Fix coredump with --overwrite and --max-size
When --overwrite and --max-size options of perf record are used together,
a segmentation fault occurs. The following is an example:
# perf record -e sched:sched* --overwrite --max-size 1M -a -- sleep 1
[ perf record: Woken up 1 times to write data ]
perf: Segmentation fault
Obtained 1 stack frames.
[0xc4c67f]
Segmentation fault (core dumped)
backtrace of the core file is as follows:
#0 0x0000000000417990 in process_locked_synthesized_event (tool=0x0, event=0x15, sample=0x1de0, machine=0xf8) at builtin-record.c:630
#1 0x000000000057ee53 in perf_event__synthesize_threads (nr_threads_synthesize=21, mmap_data=<optimized out>, needs_mmap=<optimized out>, machine=0x17ad9b0, process=<optimized out>, tool=0x0) at util/synthetic-events.c:1950
#2 __machine__synthesize_threads (nr_threads_synthesize=0, data_mmap=<optimized out>, needs_mmap=<optimized out>, process=<optimized out>, threads=0x8, target=0x8, tool=0x0, machine=0x17ad9b0) at util/synthetic-events.c:1936
#3 machine__synthesize_threads (machine=0x17ad9b0, target=0x8, threads=0x8, needs_mmap=<optimized out>, data_mmap=<optimized out>, nr_threads_synthesize=0) at util/synthetic-events.c:1947
#4 0x000000000040165d in record__synthesize (tail=<optimized out>, rec=0xbe2520 <record>) at builtin-record.c:2010
#5 0x0000000000403989 in __cmd_record (argc=<optimized out>, argv=<optimized out>, rec=0xbe2520 <record>) at builtin-record.c:2810
#6 0x00000000004196ba in record__init_thread_user_masks (rec=0xbe2520 <record>, cpus=0x17a65f0) at builtin-record.c:3837
#7 record__init_thread_masks (rec=0xbe2520 <record>) at builtin-record.c:3938
#8 cmd_record (argc=1, argv=0x7ffdd692dc60) at builtin-record.c:4241
#9 0x00000000004b701d in pager_command_config (var=0x0, value=0x15 <error: Cannot access memory at address 0x15>, data=0x1de0) at perf.c:117
#10 0x00000000004b732b in get_leaf_frame_caller_aarch64 (sample=0xfffffffb, thread=0x0, usr_idx=<optimized out>) at util/arm64-frame-pointer-unwind-support.c:56
#11 0x0000000000406331 in execv_dashed_external (argv=0x7ffdd692d9e8) at perf.c:410
#12 run_argv (argcp=<synthetic pointer>, argv=<synthetic pointer>) at perf.c:431
#13 main (argc=<optimized out>, argv=0x7ffdd692d9e8) at perf.c:562
The reason is that record__bytes_written accesses the freed memory rec->thread_data,
The process is as follows:
__cmd_record
-> record__free_thread_data
-> zfree(&rec->thread_data) // free rec->thread_data
-> record__synthesize
-> perf_event__synthesize_id_index
-> process_synthesized_event
-> record__write
-> record__bytes_written // access rec->thread_data
we only need to check the value of done first.
Also add variable check in record__bytes_written for code hardening,
and save bytes_written separately to reduce one calculation.
Fixes: 6d57581659f7 ("perf record: Add support for limit perf output file size")
Signed-off-by: Yang Jihong <yangjihong1@...wei.com>
---
Changes since v1:
- Add variable check in record__bytes_written for code hardening.
- Save bytes_written separately to reduce one calculation.
- Remove rec->opts.tail_synthesize check.
tools/perf/builtin-record.c | 26 +++++++++++++++++---------
1 file changed, 17 insertions(+), 9 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 29dcd454b8e2..acba9e43e519 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -230,16 +230,29 @@ static u64 record__bytes_written(struct record *rec)
u64 bytes_written = rec->bytes_written;
struct record_thread *thread_data = rec->thread_data;
+ if (thread_data == NULL)
+ return bytes_written;
+
for (t = 0; t < rec->nr_threads; t++)
bytes_written += thread_data[t].bytes_written;
return bytes_written;
}
-static bool record__output_max_size_exceeded(struct record *rec)
+static void record__check_output_max_size_exceeded(struct record *rec)
{
- return rec->output_max_size &&
- (record__bytes_written(rec) >= rec->output_max_size);
+ u64 bytes_written;
+
+ if (rec->output_max_size == 0 || done)
+ return;
+
+ bytes_written = record__bytes_written(rec);
+ if (bytes_written >= rec->output_max_size) {
+ fprintf(stderr, "[ perf record: perf size limit reached (%" PRIu64 " KB),"
+ " stopping session ]\n", bytes_written >> 10);
+
+ done = 1;
+ }
}
static int record__write(struct record *rec, struct mmap *map __maybe_unused,
@@ -260,12 +273,7 @@ static int record__write(struct record *rec, struct mmap *map __maybe_unused,
else
rec->bytes_written += size;
- if (record__output_max_size_exceeded(rec) && !done) {
- fprintf(stderr, "[ perf record: perf size limit reached (%" PRIu64 " KB),"
- " stopping session ]\n",
- record__bytes_written(rec) >> 10);
- done = 1;
- }
+ record__check_output_max_size_exceeded(rec);
if (switch_output_size(rec))
trigger_hit(&switch_output_trigger);
--
2.30.GIT
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