bpf: Check load-acquire src ptr type before the load

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-90312
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 17:17:28 UTC
Updated2026-10-19 09:19:25 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: bpf: Check load-acquire src ptr type before the load check_atomic_load() calls check_load_mem() before atomic_ptr_type_ok(). For a load-acquire that fetches into its own source register (dst_reg == src_reg), check_load_mem() overwrites src_reg's type with the type of the loaded value, so the subsequent atomic_ptr_type_ok() no longer sees the source pointer and fails to reject the disallowed types (ctx, pkt, flow_keys, sock). Since bpf_convert_ctx_accesses() does not rewrite atomic loads, the raw access to the underlying kernel object is left in place. The destination type is taken from the ctx access itself, so a load-acquire of the sk field of struct __sk_buff for example leaves the register typed as PTR_TO_SOCK_COMMON_OR_NULL, which type_is_sk_pointer() does not match either, while it actually holds unconverted struct sk_buff bytes. Once the NULL check has passed this is a type confusion, not just a leak of kernel data. Validate src_reg with check_reg_arg() and check the source pointer type with atomic_ptr_type_ok() before the load again, mirroring check_atomic_rmw(). Out-of-range register numbers are already rejected earlier by check_and_resolve_insns() (commit 503d21ef8eac ("bpf: Do register range validation early")), and the only exemption there, is_stack_arg_ldx(), requires BPF_LDX | BPF_MEM | BPF_DW and thus never matches a BPF_ATOMIC insn. atomic_ptr_type_ok() can therefore not dereference register state out of bounds, that is, the out-of-bounds read addressed by the Fixes commit below does not reappear (as proven also via selftest).

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001610000 probability, percentile 0.057580000 (date 2026-09-21)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected c03bb2fa327e4c25d6c5360a8803a4b1cdc2d0b9 6ee7b00888498cf387dd30729e18a05328b94709 git Not specified
CNA Linux Linux affected c03bb2fa327e4c25d6c5360a8803a4b1cdc2d0b9 422a416041172af1ac610736d5f556d22b31b115 git Not specified
CNA Linux Linux affected c03bb2fa327e4c25d6c5360a8803a4b1cdc2d0b9 b87803391baa7e0bef60549d8841f12e549ad057 git Not specified
CNA Linux Linux affected 6.15 Not specified
CNA Linux Linux unaffected 6.15 semver Not specified
CNA Linux Linux unaffected 6.18.52 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.6 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/b87803391baa7e0bef60549d8841f12e549ad057 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6ee7b00888498cf387dd30729e18a05328b94709 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/422a416041172af1ac610736d5f556d22b31b115 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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