* [PATCH][next] perf/x86/amd: fix potential integer overflow on shift of a int
@ 2022-12-02 13:51 Colin Ian King
2022-12-02 17:36 ` Ian Rogers
0 siblings, 1 reply; 3+ messages in thread
From: Colin Ian King @ 2022-12-02 13:51 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Namhyung Kim,
Thomas Gleixner, Borislav Petkov, Dave Hansen, x86,
H . Peter Anvin, Kim Phillips, linux-perf-users
Cc: kernel-janitors, linux-kernel
The left shift of int 32 bit integer constant 1 is evaluated using 32 bit
arithmetic and then passed as a 64 bit function argument. In the case where
i is 32 or more this can lead to an overflow. Avoid this by shifting
using the BIT_ULL macro instead.
Fixes: 471af006a747 ("perf/x86/amd: Constrain Large Increment per Cycle events")
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
---
arch/x86/events/amd/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index d6f3703e4119..4386b10682ce 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -1387,7 +1387,7 @@ static int __init amd_core_pmu_init(void)
* numbered counter following it.
*/
for (i = 0; i < x86_pmu.num_counters - 1; i += 2)
- even_ctr_mask |= 1 << i;
+ even_ctr_mask |= BIT_ULL(i);
pair_constraint = (struct event_constraint)
__EVENT_CONSTRAINT(0, even_ctr_mask, 0,
--
2.38.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH][next] perf/x86/amd: fix potential integer overflow on shift of a int
2022-12-02 13:51 [PATCH][next] perf/x86/amd: fix potential integer overflow on shift of a int Colin Ian King
@ 2022-12-02 17:36 ` Ian Rogers
2022-12-02 19:10 ` Kim Phillips
0 siblings, 1 reply; 3+ messages in thread
From: Ian Rogers @ 2022-12-02 17:36 UTC (permalink / raw)
To: Colin Ian King
Cc: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Namhyung Kim,
Thomas Gleixner, Borislav Petkov, Dave Hansen, x86,
H . Peter Anvin, Kim Phillips, linux-perf-users, kernel-janitors,
linux-kernel
On Fri, Dec 2, 2022 at 5:52 AM Colin Ian King <colin.i.king@gmail.com> wrote:
>
> The left shift of int 32 bit integer constant 1 is evaluated using 32 bit
> arithmetic and then passed as a 64 bit function argument. In the case where
> i is 32 or more this can lead to an overflow. Avoid this by shifting
> using the BIT_ULL macro instead.
>
> Fixes: 471af006a747 ("perf/x86/amd: Constrain Large Increment per Cycle events")
> Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Acked-by: Ian Rogers <irogers@google.com>
Thanks,
Ian
> ---
> arch/x86/events/amd/core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
> index d6f3703e4119..4386b10682ce 100644
> --- a/arch/x86/events/amd/core.c
> +++ b/arch/x86/events/amd/core.c
> @@ -1387,7 +1387,7 @@ static int __init amd_core_pmu_init(void)
> * numbered counter following it.
> */
> for (i = 0; i < x86_pmu.num_counters - 1; i += 2)
> - even_ctr_mask |= 1 << i;
> + even_ctr_mask |= BIT_ULL(i);
>
> pair_constraint = (struct event_constraint)
> __EVENT_CONSTRAINT(0, even_ctr_mask, 0,
> --
> 2.38.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH][next] perf/x86/amd: fix potential integer overflow on shift of a int
2022-12-02 17:36 ` Ian Rogers
@ 2022-12-02 19:10 ` Kim Phillips
0 siblings, 0 replies; 3+ messages in thread
From: Kim Phillips @ 2022-12-02 19:10 UTC (permalink / raw)
To: Ian Rogers, Colin Ian King
Cc: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Namhyung Kim,
Thomas Gleixner, Borislav Petkov, Dave Hansen, x86,
H . Peter Anvin, linux-perf-users, kernel-janitors, linux-kernel
On 12/2/22 11:36 AM, Ian Rogers wrote:
> On Fri, Dec 2, 2022 at 5:52 AM Colin Ian King <colin.i.king@gmail.com> wrote:
>>
>> The left shift of int 32 bit integer constant 1 is evaluated using 32 bit
>> arithmetic and then passed as a 64 bit function argument. In the case where
>> i is 32 or more this can lead to an overflow. Avoid this by shifting
>> using the BIT_ULL macro instead.
>>
>> Fixes: 471af006a747 ("perf/x86/amd: Constrain Large Increment per Cycle events")
>> Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
>
> Acked-by: Ian Rogers <irogers@google.com>
Acked-by: Kim Phillips <kim.phillips@amd.com>
Thanks,
Kim
^ permalink raw reply [flat|nested] 3+ messages in thread
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