Linux Kernel kprobes: Improper Reentry Handling & Interrupt Disabling
CVE-2026-98888 Published on October 23, 2026
arm64: kprobes: Allow reentering kprobes while single-stepping
In the Linux kernel, the following vulnerability has been resolved:
arm64: kprobes: Allow reentering kprobes while single-stepping
A kprobe can be hit while another kprobe is in KPROBE_HIT_SS state. This
can happen when tracing or perf code runs from the debug exception path
while the first kprobe is preparing or executing its out-of-line
single-step instruction.
Currently arm64 treats a kprobe hit in KPROBE_HIT_SS as unrecoverable,
the same as a hit in KPROBE_REENTER. This is too strict. A hit in
KPROBE_HIT_SS is still a one-level reentry and can be handled by saving
the current kprobe state and setting up single-step for the new probe,
just like reentry from KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE.
The truly unrecoverable case is hitting another kprobe while already in
KPROBE_REENTER, because the reentry save area has already been consumed.
Move KPROBE_HIT_SS to the recoverable reentry cases and leave
KPROBE_REENTER as the unrecoverable nested reentry case.
This change also requires saving saved_irqflag in struct prev_kprobe.
When a nested kprobe calls kprobes_save_local_irqflag(), it overwrites
kcb->saved_irqflag with the currently masked DAIF value, losing the
outer kprobe's original DAIF state. Without this fix, when the outer
kprobe's single-step finishes, kprobes_restore_local_irqflag() applies
the wrong DAIF mask and leaves interrupts permanently disabled.
Extend struct prev_kprobe with a saved_irqflag field and save/restore it
alongside kp and status. This ensures the outer kprobe's original
interrupt state is preserved across reentry.
This mirrors the x86 fix in commit 6a5022a56ac3
("kprobes/x86: Allow to handle reentered kprobe on single-stepping").
Products Associated with CVE-2026-98888
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Affected Versions
Linux:- Version 2dd0e8d2d2a157dbc83295a78336c2217110f2f8 and below bb0fe9121aa0824211aafa33c7d0151fd25ddb75 is affected.
- Version 2dd0e8d2d2a157dbc83295a78336c2217110f2f8 and below f96a0606de6bcc8d937b80e6470fd7a174c17e26 is affected.
- Version 2dd0e8d2d2a157dbc83295a78336c2217110f2f8 and below 1f342b3e44c3035a837b53b217d816f7511c0d0a is affected.
- Version 2dd0e8d2d2a157dbc83295a78336c2217110f2f8 and below c8e84e292ed4cfc199824146da71bb4397b02a1f is affected.
- Version 2dd0e8d2d2a157dbc83295a78336c2217110f2f8 and below 68774caca799e9695db56d426c69acebd041c2ed is affected.
- Version 2dd0e8d2d2a157dbc83295a78336c2217110f2f8 and below a21bf9cb893126e8d9730995708d0be5eb167652 is affected.
- Version 2dd0e8d2d2a157dbc83295a78336c2217110f2f8 and below 23f851ac0078a908bf3422d6467ebc1db5828c46 is affected.
- Version 4.8 is affected.
- Before 4.8 is unaffected.
- Version 5.10.271, <= 5.10.* is unaffected.
- Version 5.15.222, <= 5.15.* is unaffected.
- Version 6.1.189, <= 6.1.* is unaffected.
- Version 6.6.158, <= 6.6.* is unaffected.
- Version 6.12.111, <= 6.12.* is unaffected.
- Version 6.18.53, <= 6.18.* is unaffected.
- Version 7.2, <= * is unaffected.