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Message-ID: <20090913100713.GB14251@in.ibm.com>
Date: Sun, 13 Sep 2009 15:37:13 +0530
From: Ananth N Mavinakayanahalli <ananth@...ibm.com>
To: Frederic Weisbecker <fweisbec@...il.com>,
Masami Hiramatsu <mhiramat@...hat.com>
Cc: Steven Rostedt <rostedt@...dmis.org>, Ingo Molnar <mingo@...e.hu>,
lkml <linux-kernel@...r.kernel.org>,
systemtap <systemtap@...rces.redhat.com>,
DLE <dle-develop@...ts.sourceforge.net>,
Jim Keniston <jkenisto@...ibm.com>,
Andi Kleen <ak@...ux.intel.com>,
Christoph Hellwig <hch@...radead.org>,
"Frank Ch. Eigler" <fche@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, Jason Baron <jbaron@...hat.com>,
"K.Prasad" <prasad@...ux.vnet.ibm.com>,
Lai Jiangshan <laijs@...fujitsu.com>,
Li Zefan <lizf@...fujitsu.com>,
Peter Zijlstra <peterz@...radead.org>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
Tom Zanussi <tzanussi@...il.com>
Subject: [BUGFIX] kprobes: prevent re-registration of the same kprobe
On Fri, Sep 11, 2009 at 05:12:54AM +0200, Frederic Weisbecker wrote:
> On Thu, Sep 10, 2009 at 07:53:30PM -0400, Masami Hiramatsu wrote:
...
> Is it possible to have two kprobes having the exact same
> properties? (pointing to the same address, having the same
> probe handlers, etc...)
Yes, this is possible with two *different* kprobes. However, we have a bug
with the current code where there is insufficient scaffolding to prevent
re-registration of the same kprobe. Here is a patch...
---
Prevent re-registration of the same kprobe. Current code allows this,
albeit with disastrous consequences. Its not a common case, but should
be flagged nonetheless.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@...ibm.com>
---
kernel/kprobes.c | 3 +++
1 file changed, 3 insertions(+)
Index: ptrace-10sep/kernel/kprobes.c
===================================================================
--- ptrace-10sep.orig/kernel/kprobes.c
+++ ptrace-10sep/kernel/kprobes.c
@@ -589,6 +589,9 @@ static int __kprobes register_aggr_kprob
int ret = 0;
struct kprobe *ap = old_p;
+ if (old_p == p)
+ /* Attempt to re-register the same kprobe.. fail */
+ return -EINVAL;
if (old_p->pre_handler != aggr_pre_handler) {
/* If old_p is not an aggr_probe, create new aggr_kprobe. */
ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
--
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