diff options
| author | Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> | 2014-08-04 03:10:16 +0000 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-08-08 10:38:04 +0200 |
| commit | f96f56780ca584930bb3a2769d73fd9a101bcbbe (patch) | |
| tree | c3974ec34ef0e249e25819248d84b8ec2c80325c | |
| parent | 98a96f202203fecad65b44449077c695686ad4db (diff) | |
kprobes: Skip kretprobe hit in NMI context to avoid deadlock
Skip kretprobe hit in NMI context, because if an NMI happens
inside the critical section protected by kretprobe_table.lock
and another(or same) kretprobe hit, pre_kretprobe_handler
tries to lock kretprobe_table.lock again.
Normal interrupts have no problem because they are disabled
with the lock.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Link: http://lkml.kernel.org/r/20140804031016.11433.65539.stgit@kbuild-fedora.novalocal
[ Minor edits for clarity. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | kernel/kprobes.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 734e9a7d280b..3995f546d0f3 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1778,7 +1778,18 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) unsigned long hash, flags = 0; struct kretprobe_instance *ri; - /*TODO: consider to only swap the RA after the last pre_handler fired */ + /* + * To avoid deadlocks, prohibit return probing in NMI contexts, + * just skip the probe and increase the (inexact) 'nmissed' + * statistical counter, so that the user is informed that + * something happened: + */ + if (unlikely(in_nmi())) { + rp->nmissed++; + return 0; + } + + /* TODO: consider to only swap the RA after the last pre_handler fired */ hash = hash_ptr(current, KPROBE_HASH_BITS); raw_spin_lock_irqsave(&rp->lock, flags); if (!hlist_empty(&rp->free_instances)) { |