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authorAnanth N Mavinakayanahalli <ananth@in.ibm.com>2006-02-03 03:03:43 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-03 08:32:00 -0800
commit278ff9537030bbb292b33504f5e1f6e0126793eb (patch)
tree0087828bdf4d9a4fb57c9bcafd068ff058b39797
parente65cefe87beda627c0bfba39b387ee4bffedc93c (diff)
downloadop-kernel-dev-278ff9537030bbb292b33504f5e1f6e0126793eb.zip
op-kernel-dev-278ff9537030bbb292b33504f5e1f6e0126793eb.tar.gz
[PATCH] Kprobes: Fix deadlock in function-return probes
When two function-return probes are inserted on kfree()[1] and the second on say, sys_link()[2], and later [2] is unregistered, we have a deadlock as kfree is called with the kretprobe_lock held and the function-return probe on kfree will also try to grab the same lock. However, we can move the kfree() during unregistration to outside the spinlock as we are sure that no instances from the free list will be used after synchronized_sched() returns during the unregistration process. Thanks to Masami Hiramatsu for spotting this. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--kernel/kprobes.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 95ad7f8..fef1af8 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -631,12 +631,12 @@ void __kprobes unregister_kretprobe(struct kretprobe *rp)
unregister_kprobe(&rp->kp);
/* No race here */
spin_lock_irqsave(&kretprobe_lock, flags);
- free_rp_inst(rp);
while ((ri = get_used_rp_inst(rp)) != NULL) {
ri->rp = NULL;
hlist_del(&ri->uflist);
}
spin_unlock_irqrestore(&kretprobe_lock, flags);
+ free_rp_inst(rp);
}
static int __init init_kprobes(void)
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