linux-kernel - [070/107] kmod: prevent kmod_loop_msg overflow in __request

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Message-Id: <20111102221456.513177008@clark.kroah.org>
Date:	Wed, 02 Nov 2011 15:14:36 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Jiri Kosina <jkosina@...e.cz>,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: [070/107] kmod: prevent kmod_loop_msg overflow in __request_module()

2.6.32-longterm review patch.  If anyone has any objections, please let us know.

------------------

From: Jiri Kosina <jkosina@...e.cz>

commit 37252db6aa576c34fd794a5a54fb32d7a8b3a07a upstream.

Due to post-increment in condition of kmod_loop_msg in __request_module(),
the system log can be spammed by much more than 5 instances of the 'runaway
loop' message if the number of events triggering it makes the kmod_loop_msg
to overflow.

Fix that by making sure we never increment it past the threshold.

Signed-off-by: Jiri Kosina <jkosina@...e.cz>
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 kernel/kmod.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -106,10 +106,12 @@ int __request_module(bool wait, const ch
 	atomic_inc(&kmod_concurrent);
 	if (atomic_read(&kmod_concurrent) > max_modprobes) {
 		/* We may be blaming an innocent here, but unlikely */
-		if (kmod_loop_msg++ < 5)
+		if (kmod_loop_msg < 5) {
 			printk(KERN_ERR
 			       "request_module: runaway loop modprobe %s\n",
 			       module_name);
+			kmod_loop_msg++;
+		}
 		atomic_dec(&kmod_concurrent);
 		return -ENOMEM;
 	}


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