| Message ID | 20210303071052.33740-1-huangshaobo6@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [4.9.y] arm: kprobes: Allow to handle reentered kprobe on single-stepping | expand |
On Wed, Mar 03, 2021 at 09:18:27PM +0900, Masami Hiramatsu wrote: > Hi ShaoBo, > > Thanks for backporting and real bug report! > > On Wed, 3 Mar 2021 15:10:52 +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 > > Also queued up to 4.4.y as well. thanks, greg k-h
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();