x86/kprobes: Fix crash when probing CS CALL instructions

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Summary

CVECVE-2026-98273
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-06 09:18:16 UTC
Updated2026-10-19 10:18:28 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: x86/kprobes: Fix crash when probing CS CALL instructions When using eBPF to probe CS CALL instructions within a function, a crash can be triggered. The eBPF tool probes offset 257 of the __hrtimer_run_queues() function: <__hrtimer_run_queues+249>: nopl 0x0(%rax,%rax,1) <__hrtimer_run_queues+254>: mov %r14,%rdi <__hrtimer_run_queues+257>: cs call <__x86_indirect_thunk_r12> <__hrtimer_run_queues+263>: mov %eax,%r12d <__hrtimer_run_queues+266>: xchg %ax,%ax <__hrtimer_run_queues+268>: mov %r13,%rdi Which triggers this crash: BUG: unable to handle page fault for address: 00000000000f41c9 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP NOPTI CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P RIP: 0010:__hrtimer_run_queues+0x106/0x230 Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is at the 6th byte of the above CS CALL instruction. Since the CS CALL instruction occupies 6 bytes, the exception occurred in the middle of that call instruction. The root cause is that when using eBPF tools to probe in the middle of a function, a kprobe with INT3 is used as the underlying implementation. During single-step emulation of the original CALL instruction, int3_emulate_call() assumes that the probed CALL instruction is 5 bytes long. However, the actual CS-prefixed CALL instruction occupies 6 bytes, so it constructs an incorrect exception return address. When the CPU returns from the kprobe handler, the next instruction to be executed is at the address of the last byte of that CS CALL instruction. Coincidentally, starting from that address, the CPU fetches and decodes a completely different instruction, which ultimately triggers a kernel crash. Fix the issue by using the actual instruction length obtained from the instruction decoder when constructing the exception return address, rather than relying on the hardcoded CALL_INSN_SIZE macro. [ mingo: Refined the changelog ]

Risk And Classification

EPSS: 0.001730000 probability, percentile 0.061520000 (date 2026-10-06)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 6256e668b7af9d81472e03c6a171630c08f8858a cfc1af3d054aaabee08f1f77c441b3533b082869 git Not specified
CNA Linux Linux affected 6256e668b7af9d81472e03c6a171630c08f8858a d8c6a18c0552135cbf0c696c9019b2979d0862c9 git Not specified
CNA Linux Linux affected 6256e668b7af9d81472e03c6a171630c08f8858a a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 git Not specified
CNA Linux Linux affected ba7d1dae9fe866abe74bb1e849fb85983b7c4c37 git Not specified
CNA Linux Linux affected 5.10.190 5.11 semver Not specified
CNA Linux Linux affected 5.13 Not specified
CNA Linux Linux unaffected 5.13 semver Not specified
CNA Linux Linux unaffected 6.18.54 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.8 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/cfc1af3d054aaabee08f1f77c441b3533b082869 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d8c6a18c0552135cbf0c696c9019b2979d0862c9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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