[PATCH 5.19 002/101] tools/perf: Fix out of bound access to cpu mask array

From: Greg Kroah-Hartman
Date: Mon Oct 03 2022 - 03:13:54 EST

From: Athira Rajeev <atrajeev@xxxxxxxxxxxxxxxxxx>

[ Upstream commit cbd7bfc7fd99acdde58ec2b0bce990158fba1654 ]

The cpu mask init code in "record__mmap_cpu_mask_init" function access
"bits" array part of "struct mmap_cpu_mask". The size of this array is
the value from cpu__max_cpu().cpu. This array is used to contain the
cpumask value for each cpu. While setting bit for each cpu, it calls
"set_bit" function which access index in "bits" array.

If we provide a command line option to -C which is greater than the
number of CPU's present in the system, the set_bit could access an array
member which is out-of the array size. This is because currently, there
is no boundary check for the CPU. This will result in seg fault:

./perf record -C 12341234 ls
Perf can support 2048 CPUs. Consider raising MAX_NR_CPUS
Segmentation fault (core dumped)

Debugging with gdb, points to function flow as below:


Fix this by adding boundary check for the array.

After the patch:

./perf record -C 12341234 ls
Perf can support 2048 CPUs. Consider raising MAX_NR_CPUS
Failed to initialize parallel data streaming masks

With this fix, if -C is given a non-exsiting CPU, perf
record will fail with:

./perf record -C 50 ls
Failed to initialize parallel data streaming masks

Reported-by: Nageswara R Sastry <rnsastry@xxxxxxxxxxxxx>
Signed-off-by: Athira Jajeev <atrajeev@xxxxxxxxxxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Tested-by: Nageswara R Sastry <rnsastry@xxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kajol Jain <kjain@xxxxxxxxxxxxx>
Cc: Madhavan Srinivasan <maddy@xxxxxxxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20220905141929.7171-2-atrajeev@xxxxxxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Stable-dep-of: ca76d7d2812b ("perf record: Fix cpu mask bit setting for mixed mmaps")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
tools/perf/builtin-record.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 68c878b4e5e4..708880a1c83c 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -3335,16 +3335,22 @@ static struct option __record_options[] = {

struct option *record_options = __record_options;

-static void record__mmap_cpu_mask_init(struct mmap_cpu_mask *mask, struct perf_cpu_map *cpus)
+static int record__mmap_cpu_mask_init(struct mmap_cpu_mask *mask, struct perf_cpu_map *cpus)
struct perf_cpu cpu;
int idx;

if (cpu_map__is_dummy(cpus))
- return;
+ return 0;

- perf_cpu_map__for_each_cpu(cpu, idx, cpus)
+ perf_cpu_map__for_each_cpu(cpu, idx, cpus) {
+ /* Return ENODEV is input cpu is greater than max cpu */
+ if ((unsigned long)cpu.cpu > mask->nbits)
+ return -ENODEV;
set_bit(cpu.cpu, mask->bits);
+ }
+ return 0;

static int record__mmap_cpu_mask_init_spec(struct mmap_cpu_mask *mask, const char *mask_spec)
@@ -3356,7 +3362,9 @@ static int record__mmap_cpu_mask_init_spec(struct mmap_cpu_mask *mask, const cha
return -ENOMEM;

bitmap_zero(mask->bits, mask->nbits);
- record__mmap_cpu_mask_init(mask, cpus);
+ if (record__mmap_cpu_mask_init(mask, cpus))
+ return -ENODEV;

return 0;
@@ -3438,7 +3446,12 @@ static int record__init_thread_masks_spec(struct record *rec, struct perf_cpu_ma
pr_err("Failed to allocate CPUs mask\n");
return ret;
- record__mmap_cpu_mask_init(&cpus_mask, cpus);
+ ret = record__mmap_cpu_mask_init(&cpus_mask, cpus);
+ if (ret) {
+ pr_err("Failed to init cpu mask\n");
+ goto out_free_cpu_mask;
+ }

ret = record__thread_mask_alloc(&full_mask, cpu__max_cpu().cpu);
if (ret) {
@@ -3679,7 +3692,8 @@ static int record__init_thread_default_masks(struct record *rec, struct perf_cpu
if (ret)
return ret;

- record__mmap_cpu_mask_init(&rec->thread_masks->maps, cpus);
+ if (record__mmap_cpu_mask_init(&rec->thread_masks->maps, cpus))
+ return -ENODEV;

rec->nr_threads = 1;