Bug 2492781 (CVE-2026-53172)

Summary: CVE-2026-53172 kernel: accel/ethosu: fix IFM region index out-of-bounds in command stream parser
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's accel/ethosu component. An incorrect mask used when processing the NPU_SET_IFM_REGION command allows a local userspace caller to provide an out-of-bounds region index. This can lead to an out-of-bounds write, corrupting adjacent kernel heap data.
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Description OSIDB Bzimport 2026-06-25 10:05:23 UTC 
In the Linux kernel, the following vulnerability has been resolved:

accel/ethosu: fix IFM region index out-of-bounds in command stream parser

NPU_SET_IFM_REGION extracts the region index with param & 0x7f, giving
a maximum value of 127. However region_size[] and output_region[] in
struct ethosu_validated_cmdstream_info are both sized to
NPU_BASEP_REGION_MAX (8), giving valid indices [0..7].

Every other region assignment in the same switch uses param & 0x7:
  NPU_SET_OFM_REGION:  st.ofm.region  = param & 0x7;
  NPU_SET_IFM2_REGION: st.ifm2.region = param & 0x7;
  NPU_SET_WEIGHT_REGION: st.weight[0].region = param & 0x7;
  NPU_SET_SCALE_REGION:  st.scale[0].region  = param & 0x7;

The 0x7f mask on IFM is inconsistent and appears to be a typo.

feat_matrix_length() and calc_sizes() use the region index directly
as an array subscript into the kzalloc'd info struct:
  info->region_size[fm->region] = max(...);

A userspace caller supplying NPU_SET_IFM_REGION with param > 7 causes
a write up to 127*8 = 1016 bytes past the start of region_size[],
corrupting adjacent kernel heap data.

Fix by applying the same & 0x7 mask used by all other region
assignments.
Comment 1 Keith Grant 2026-06-26 00:11:08 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062552-CVE-2026-53172-11a3@gregkh/T