* [PATCH V2 2/2] tools/perf: Fix out of bound access to cpu mask array
2022-09-05 14:19 [PATCH V2 1/2] tools/perf: Fix out of bound access to affinity "sched_cpus" Athira Rajeev
@ 2022-09-05 14:19 ` Athira Rajeev
2022-09-06 12:27 ` [PATCH V2 1/2] tools/perf: Fix out of bound access to affinity "sched_cpus" Arnaldo Carvalho de Melo
1 sibling, 0 replies; 3+ messages in thread
From: Athira Rajeev @ 2022-09-05 14:19 UTC (permalink / raw)
To: acme, jolsa; +Cc: mpe, linux-perf-users, linuxppc-dev, maddy, rnsastry, kjain
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:
<<>>
set_bit
record__mmap_cpu_mask_init
record__init_thread_default_masks
record__init_thread_masks
cmd_record
<<>>
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 Sastry <rnsastry@linux.ibm.com>
Tested-by: Nageswara Sastry <rnsastry@linux.ibm.com>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
---
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 4713f0f3a6cf..09b68d76bbdc 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -3358,16 +3358,22 @@ 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)
@@ -3379,7 +3385,9 @@ 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;
+
perf_cpu_map__put(cpus);
return 0;
@@ -3461,7 +3469,12 @@ 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) {
@@ -3702,7 +3715,8 @@ 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;
--
2.35.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH V2 1/2] tools/perf: Fix out of bound access to affinity "sched_cpus"
2022-09-05 14:19 [PATCH V2 1/2] tools/perf: Fix out of bound access to affinity "sched_cpus" Athira Rajeev
2022-09-05 14:19 ` [PATCH V2 2/2] tools/perf: Fix out of bound access to cpu mask array Athira Rajeev
@ 2022-09-06 12:27 ` Arnaldo Carvalho de Melo
1 sibling, 0 replies; 3+ messages in thread
From: Arnaldo Carvalho de Melo @ 2022-09-06 12:27 UTC (permalink / raw)
To: Athira Rajeev
Cc: jolsa, mpe, linux-perf-users, linuxppc-dev, maddy, rnsastry,
kjain
Em Mon, Sep 05, 2022 at 07:49:28PM +0530, Athira Rajeev escreveu:
> The affinity code in "affinity_set" function access array
> named "sched_cpus". The size for this array is allocated in
> affinity_setup function which is nothing but value from
> get_cpu_set_size. This 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 sched_cpus array.
> If we provide a command-line option to -C which is more 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:
Thanks, tested, reproduced the problem before, and the fix after,
applied.
- Arnaldo
> <<>>
> ./perf stat -C 12323431 ls
> Perf can support 2048 CPUs. Consider raising MAX_NR_CPUS
> Segmentation fault (core dumped)
> <<>>
>
> Fix this by adding boundary check for the array.
>
> After the fix from powerpc system:
>
> <<>>
> ./perf stat -C 12323431 ls 1>out
> Perf can support 2048 CPUs. Consider raising MAX_NR_CPUS
>
> Performance counter stats for 'CPU(s) 12323431':
>
> <not supported> msec cpu-clock
> <not supported> context-switches
> <not supported> cpu-migrations
> <not supported> page-faults
> <not supported> cycles
> <not supported> instructions
> <not supported> branches
> <not supported> branch-misses
>
> 0.001192373 seconds time elapsed
> <<>>
>
> Reported-by: Nageswara Sastry <rnsastry@linux.ibm.com>
> Tested-by: Nageswara Sastry <rnsastry@linux.ibm.com>
> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
> ---
> Changelog:
> From v1 -> v2:
> Addressed review comment from Jiri Olsa by changing condition
> check to directly use "cpu_set_size * 8" for comparing with the
> cpu number.
>
> tools/perf/util/affinity.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/affinity.c b/tools/perf/util/affinity.c
> index 4d216c0dc425..4ee96b3c755b 100644
> --- a/tools/perf/util/affinity.c
> +++ b/tools/perf/util/affinity.c
> @@ -49,8 +49,14 @@ void affinity__set(struct affinity *a, int cpu)
> {
> int cpu_set_size = get_cpu_set_size();
>
> - if (cpu == -1)
> + /*
> + * Return:
> + * - if cpu is -1
> + * - restrict out of bound access to sched_cpus
> + */
> + if (cpu == -1 || ((cpu >= (cpu_set_size * 8))))
> return;
> +
> a->changed = true;
> set_bit(cpu, a->sched_cpus);
> /*
> --
> 2.35.1
--
- Arnaldo
^ permalink raw reply [flat|nested] 3+ messages in thread