perf: Fix overflow in PERF_IDX2OFF() for Arm SPE and TRBE drivers

[PATCH 0/2] perf: Fix overflow in PERF_IDX2OFF() for Arm SPE and TRBE drivers

Posted by Leo Yan 2 weeks ago

If the AUX buffer size is specified as 2 GiB or larger, the expression
"(buf)->nr_pages << PAGE_SHIFT" may exceed 0x8000_0000. Since
(buf)->nr_pages is a signed integer, the shift can overflow and produce
a negative value. As a result, PERF_IDX2OFF() fails to work correctly.

Fix this by casting (buf)->nr_pages to unsigned long before the shift,
which allows PERF_IDX2OFF() to handle large buffers properly.

Signed-off-by: Leo Yan <leo.yan@arm.com>
---
Leo Yan (2):
      coresight: trbe: Prevent overflow in PERF_IDX2OFF()
      perf: arm_spe: Prevent overflow in PERF_IDX2OFF()

 drivers/hwtracing/coresight/coresight-trbe.c | 3 ++-
 drivers/perf/arm_spe_pmu.c                   | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)
---
base-commit: 5aca7966d2a7255ba92fd5e63268dd767b223aa5
change-id: 20250917-fix_aux_trace_index-9745674f5061

Best regards,
-- 
Leo Yan <leo.yan@arm.com>

Re: [PATCH 0/2] perf: Fix overflow in PERF_IDX2OFF() for Arm SPE and TRBE drivers

Posted by Will Deacon 1 week, 6 days ago

On Wed, 17 Sep 2025 18:41:37 +0100, Leo Yan wrote:
> If the AUX buffer size is specified as 2 GiB or larger, the expression
> "(buf)->nr_pages << PAGE_SHIFT" may exceed 0x8000_0000. Since
> (buf)->nr_pages is a signed integer, the shift can overflow and produce
> a negative value. As a result, PERF_IDX2OFF() fails to work correctly.
> 
> Fix this by casting (buf)->nr_pages to unsigned long before the shift,
> which allows PERF_IDX2OFF() to handle large buffers properly.
> 
> [...]

Applied to will (for-next/perf), thanks!

[1/2] coresight: trbe: Prevent overflow in PERF_IDX2OFF()
      https://git.kernel.org/will/c/105f56877f2d
[2/2] perf: arm_spe: Prevent overflow in PERF_IDX2OFF()
      https://git.kernel.org/will/c/a29fea30dd93

Cheers,
-- 
Will

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