Re: Automount causes zero-pointer dereference in 2.6.36-rc2
From: Suresh Jayaraman
Date: Wed Aug 25 2010 - 07:58:58 EST
On 08/25/2010 03:50 AM, Christopher K. wrote:
> Hi,
> I'm using autofs to mount some cifs shares in my /home.
> Running 2.6.36-rc2-git2, browsing /home results in the following error:
>
> BUG: unable to handle kernel NULL pointer dereference at (null)
> IP: [<c124a921>] strncmp+0x11/0x30
> *pde = 00000000
> Oops: 0000 [#1] SMP
> last sysfs file: /sys/devices/virtual/bdi/cifs-5/uevent
> Modules linked in:
> Pid: 3496, comm: mount.cifs Not tainted 2.6.36-rc2-git2 #2 K50IJ
> EIP: 0060:[<c124921>] EFLAGS: 00010216 CPU: 1
> EIP is at strncmp+0x11/0x30
> EAX: 00000000 EBX: f3a5d200 ECX: 000001ff EDX: 00000000
> ESI: 00000000 EDI: 00000000 EBP: f3a98408 ESP: f3acde38
> DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
> Process mount.cifs (pid: 3496, ti=f3acc000, task=f5adc800, task.ti=f3acc000)
> Stack:
> f3a98400f5a24080 c119f122 00000000 00000000 00000000 00000000 00000000
> <0> 00003674 00000000 00000000 f3a7f02e f5a24080 c17d4320 f5a837c0 c119f784
> <0> c15c4280 f3acdea0 00000000 f3b2ae30 f3acdea4 f3b2ae00 00003673 f3b2ae30
> Call Trace:
> ...cifs_get_smb_ses...
> ...cifs_mount...
> ...kmem_cache_alloc...
> ...cifs_get_sb...
> ...vfs_kern_mount...
> ...get_fs_type...
> ...do_kern_mount...
> ...do_mount...
> ...copy_mount_options...
> ...sys_mount...
> ...sysenter_do_call...
>
(Cc-ing linux-cifs@vger@kernel.org)
Does the following patch fixes the problem for you? This patch has been included
in the cifs development git and should be available in the next -rc.
Subject: [PATCH] cifs: check for NULL session password
From: Jeff Layton <jlayton@xxxxxxxxxx>
Date: Mon, 23 Aug 2010 11:38:04 -0400
To: smfrench@xxxxxxxxx
CC: linux-cifs@xxxxxxxxxxxxxxx
It's possible for a cifsSesInfo struct to have a NULL password, so we
need to check for that prior to running strncmp on it.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/cifs/connect.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 18af707..ec0ea4a 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1673,6 +1673,7 @@ cifs_find_smb_ses(struct TCP_Server_Info *server, struct smb_vol *vol)
MAX_USERNAME_SIZE))
continue;
if (strlen(vol->username) != 0 &&
+ ses->password != NULL &&
strncmp(ses->password,
vol->password ? vol->password : "",
MAX_PASSWORD_SIZE))
--
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