Bug 2466789 (CVE-2026-43070) - CVE-2026-43070 kernel: bpf: Reset register ID for BPF_END value tracking
Summary: CVE-2026-43070 kernel: bpf: Reset register ID for BPF_END value tracking
Keywords:
Status: NEW
Alias: CVE-2026-43070
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-05-05 17:02 UTC by OSIDB Bzimport
Modified: 2026-05-06 09:48 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
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Description OSIDB Bzimport 2026-05-05 17:02:51 UTC
In the Linux kernel, the following vulnerability has been resolved:

bpf: Reset register ID for BPF_END value tracking

When a register undergoes a BPF_END (byte swap) operation, its scalar
value is mutated in-place. If this register previously shared a scalar ID
with another register (e.g., after an `r1 = r0` assignment), this tie must
be broken.

Currently, the verifier misses resetting `dst_reg->id` to 0 for BPF_END.
Consequently, if a conditional jump checks the swapped register, the
verifier incorrectly propagates the learned bounds to the linked register,
leading to false confidence in the linked register's value and potentially
allowing out-of-bounds memory accesses.

Fix this by explicitly resetting `dst_reg->id` to 0 in the BPF_END case
to break the scalar tie, similar to how BPF_NEG handles it via
`__mark_reg_known`.


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