From patchwork Tue Oct 2 19:22:11 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [Lucid,SRU] 9p: Fix the kernel crash on a failed mount Date: Tue, 02 Oct 2012 09:22:11 -0000 From: Tim Gardner X-Patchwork-Id: 188636 Message-Id: <1349205731-78572-1-git-send-email-tim.gardner@canonical.com> To: kernel-team@lists.ubuntu.com From: "Aneesh Kumar K.V" BugLink: http://bugs.launchpad.net/bugs/676823 The patch fix the crash repoted below [ 15.149907] BUG: unable to handle kernel NULL pointer dereference at 00000001 [ 15.150806] IP: [] p9_virtio_close+0x18/0x24 ..... .... [ 15.150806] Call Trace: [ 15.150806] [] ? p9_client_destroy+0x3f/0x163 [ 15.150806] [] ? p9_client_create+0x25f/0x270 [ 15.150806] [] ? trace_hardirqs_on+0xb/0xd [ 15.150806] [] ? match_token+0x64/0x164 [ 15.150806] [] ? v9fs_session_init+0x2f1/0x3c8 [ 15.150806] [] ? kmem_cache_alloc+0x98/0xb8 [ 15.150806] [] ? trace_hardirqs_on+0xb/0xd [ 15.150806] [] ? v9fs_get_sb+0x47/0x1e8 [ 15.150806] [] ? v9fs_get_sb+0x60/0x1e8 [ 15.150806] [] ? vfs_kern_mount+0x81/0x11a [ 15.150806] [] ? do_kern_mount+0x33/0xbe [ 15.150806] [] ? do_mount+0x654/0x6b3 [ 15.150806] [] ? do_page_fault+0x0/0x284 [ 15.150806] [] ? copy_mount_options+0x73/0xd2 [ 15.150806] [] ? sys_mount+0x61/0x94 [ 15.150806] [] ? syscall_call+0x7/0xb .... [ 15.203562] ---[ end trace 1dd159357709eb4b ]--- [ Signed-off-by: Aneesh Kumar K.V Signed-off-by: Eric Van Hensbergen (cherry picked from commit fb786100f7c75e154e63d0f5a2982e6d46dfb602) Signed-off-by: Tim Gardner Acked-by: Colin Ian King --- net/9p/trans_virtio.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index 67c4bc7..cb50f4a 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -102,7 +102,8 @@ static void p9_virtio_close(struct p9_client *client) struct virtio_chan *chan = client->trans; mutex_lock(&virtio_9p_lock); - chan->inuse = false; + if (chan) + chan->inuse = false; mutex_unlock(&virtio_9p_lock); }