Messages in this thread | | | Subject | Re: [PATCH 4.4.y] arm: kprobes: Allow to handle reentered kprobe on single-stepping | From | Xiaoming Ni <> | Date | Fri, 9 Jul 2021 19:39:30 +0800 |
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On 2021/7/9 17:00, Masami Hiramatsu wrote: > Hi Shaobo, > > Thanks for backporting! > Greg, it seems this patch can be applied to 4.9 too without any issue. > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.9.y&id=355a04fa1fc23c4fb1d16440e62d46a42691e96b
The v4.9 branch has been fixed.
Thanks Xiaoming Ni
> Thank you, > > On Fri, 9 Jul 2021 10:46:30 +0800 > Shaobo Huang <huangshaobo6@huawei.com> wrote: > >> From: Masami Hiramatsu <mhiramat@kernel.org> >> >> commit f3fbd7ec62dec1528fb8044034e2885f2b257941 upstream >> >> This is arm port of commit 6a5022a56ac3 ("kprobes/x86: Allow to >> handle reentered kprobe on single-stepping") >> >> Since the FIQ handlers can interrupt in the single stepping >> (or preparing the single stepping, do_debug etc.), we should >> consider a kprobe is hit in the NMI handler. Even in that >> case, the kprobe is allowed to be reentered as same as the >> kprobes hit in kprobe handlers >> (KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE). >> >> The real issue will happen when a kprobe hit while another >> reentered kprobe is processing (KPROBE_REENTER), because >> we already consumed a saved-area for the previous kprobe. >> >> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> >> Signed-off-by: Jon Medhurst <tixy@linaro.org> >> Fixes: 24ba613c9d6c ("ARM kprobes: core code") >> Cc: stable@vger.kernel.org #v2.6.25~v4.11 >> Signed-off-by: huangshaobo <huangshaobo6@huawei.com> >> --- >> arch/arm/probes/kprobes/core.c | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c >> index 3eb018fa1a1f..c3362ddd6c4c 100644 >> --- a/arch/arm/probes/kprobes/core.c >> +++ b/arch/arm/probes/kprobes/core.c >> @@ -270,6 +270,7 @@ void __kprobes kprobe_handler(struct pt_regs *regs) >> switch (kcb->kprobe_status) { >> case KPROBE_HIT_ACTIVE: >> case KPROBE_HIT_SSDONE: >> + case KPROBE_HIT_SS: >> /* A pre- or post-handler probe got us here. */ >> kprobes_inc_nmissed_count(p); >> save_previous_kprobe(kcb); >> @@ -278,6 +279,11 @@ void __kprobes kprobe_handler(struct pt_regs *regs) >> singlestep(p, regs, kcb); >> restore_previous_kprobe(kcb); >> break; >> + case KPROBE_REENTER: >> + /* A nested probe was hit in FIQ, it is a BUG */ >> + pr_warn("Unrecoverable kprobe detected at %p.\n", >> + p->addr); >> + /* fall through */ >> default: >> /* impossible cases */ >> BUG(); >> -- >> 2.12.3 >> > >
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