Patch "netlink: put module reference if dump start fails" has been added to the 4.15-stable tree

Patch "netlink: put module reference if dump start fails" has been added to the 4.15-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    netlink: put module reference if dump start fails

to the 4.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     netlink-put-module-reference-if-dump-start-fails.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Tue Mar  6 19:02:56 PST 2018
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Wed, 21 Feb 2018 04:41:59 +0100
Subject: netlink: put module reference if dump start fails

From: "Jason A. Donenfeld" <Jason@zx2c4.com>


[ Upstream commit b87b6194be631c94785fe93398651e804ed43e28 ]

Before, if cb->start() failed, the module reference would never be put,
because cb->cb_running is intentionally false at this point. Users are
generally annoyed by this because they can no longer unload modules that
leak references. Also, it may be possible to tediously wrap a reference
counter back to zero, especially since module.c still uses atomic_inc
instead of refcount_inc.

This patch expands the error path to simply call module_put if
cb->start() fails.

Fixes: 41c87425a1ac ("netlink: do not set cb_running if dump's start() errs")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/netlink/af_netlink.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2275,7 +2275,7 @@ int __netlink_dump_start(struct sock *ss
 	if (cb->start) {
 		ret = cb->start(cb);
 		if (ret)
-			goto error_unlock;
+			goto error_put;
 	}
 
 	nlk->cb_running = true;
@@ -2295,6 +2295,8 @@ int __netlink_dump_start(struct sock *ss
 	 */
 	return -EINTR;
 
+error_put:
+	module_put(control->module);
 error_unlock:
 	sock_put(sk);
 	mutex_unlock(nlk->cb_mutex);


Patches currently in stable-queue which might be from Jason@zx2c4.com are

queue-4.15/netlink-put-module-reference-if-dump-start-fails.patch