On Tue 22-11-11 11:00:20, Dan Carpenter wrote:
> This is an fsfuzzer bug. ->s_journal is set at the end of
> ext3_load_journal() but we try to use it in the error handling from
> ext3_get_journal() while it's still NULL.
Thanks, I've merged the patch and added a comment before the check
explaining why the s_journal check is needed.
Honza
>
> [ 337.039041] BUG: unable to handle kernel NULL pointer dereference at 0000000000000024
> [ 337.040380] IP: [<ffffffff816e6539>] _raw_spin_lock+0x9/0x30
> [ 337.041687] PGD 0
> [ 337.043118] Oops: 0002 [#1] SMP
> [ 337.044483] CPU 3
> [ 337.044495] Modules linked in: ecb md4 cifs fuse kvm_intel kvm brcmsmac brcmutil crc8 cordic r8169 [last unloaded: scsi_wait_scan]
> [ 337.047633]
> [ 337.049259] Pid: 8308, comm: mount Not tainted 3.2.0-rc2-next-20111121+ #24 SAMSUNG ELECTRONICS CO., LTD. RV411/RV511/E3511/S3511 /RV411/RV511/E3511/S3511
> [ 337.051064] RIP: 0010:[<ffffffff816e6539>] [<ffffffff816e6539>] _raw_spin_lock+0x9/0x30
> [ 337.052879] RSP: 0018:ffff8800b1d11ae8 EFLAGS: 00010282
> [ 337.054668] RAX: 0000000000000100 RBX: 0000000000000000 RCX: ffff8800b77c2000
> [ 337.056400] RDX: ffff8800a97b5c00 RSI: 0000000000000000 RDI: 0000000000000024
> [ 337.058099] RBP: ffff8800b1d11ae8 R08: 6000000000000000 R09: e018000000000000
> [ 337.059841] R10: ff67366cc2607c03 R11: 00000000110688e6 R12: 0000000000000000
> [ 337.061607] R13: 0000000000000000 R14: 0000000000000000 R15: ffff8800a78f06e8
> [ 337.063385] FS: 00007f9d95652800(0000) GS:ffff8800b7180000(0000) knlGS:0000000000000000
> [ 337.065110] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 337.066801] CR2: 0000000000000024 CR3: 00000000aef2c000 CR4: 00000000000006e0
> [ 337.068581] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 337.070321] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [ 337.072105] Process mount (pid: 8308, threadinfo ffff8800b1d10000, task ffff8800b1d02be0)
> [ 337.073800] Stack:
> [ 337.075487] ffff8800b1d11b08 ffffffff811f48cf ffff88007ac9b158 0000000000000000
> [ 337.077255] ffff8800b1d11b38 ffffffff8119405d ffff88007ac9b158 ffff88007ac9b250
> [ 337.078851] ffffffff8181bda0 ffffffff8181bda0 ffff8800b1d11b68 ffffffff81131e31
> [ 337.080284] Call Trace:
> [ 337.081706] [<ffffffff811f48cf>] log_start_commit+0x1f/0x40
> [ 337.083107] [<ffffffff8119405d>] ext3_evict_inode+0x1fd/0x2a0
> [ 337.084490] [<ffffffff81131e31>] evict+0xa1/0x1a0
> [ 337.085857] [<ffffffff81132031>] iput+0x101/0x210
> [ 337.087220] [<ffffffff811339d1>] iget_failed+0x21/0x30
> [ 337.088581] [<ffffffff811905fc>] ext3_iget+0x15c/0x450
> [ 337.089936] [<ffffffff8118b0c1>] ? ext3_rsv_window_add+0x81/0x100
> [ 337.091284] [<ffffffff816df9a4>] ext3_get_journal+0x15/0xde
> [ 337.092641] [<ffffffff811a2e9b>] ext3_fill_super+0xf2b/0x1c30
> [ 337.093991] [<ffffffff810ddf7d>] ? register_shrinker+0x4d/0x60
> [ 337.095332] [<ffffffff8111c112>] mount_bdev+0x1a2/0x1e0
> [ 337.096680] [<ffffffff811a1f70>] ? ext3_setup_super+0x210/0x210
> [ 337.098026] [<ffffffff8119a770>] ext3_mount+0x10/0x20
> [ 337.099362] [<ffffffff8111cbee>] mount_fs+0x3e/0x1b0
> [ 337.100759] [<ffffffff810eda1b>] ? __alloc_percpu+0xb/0x10
> [ 337.102330] [<ffffffff81135385>] vfs_kern_mount+0x65/0xc0
> [ 337.103889] [<ffffffff8113611f>] do_kern_mount+0x4f/0x100
> [ 337.105442] [<ffffffff811378fc>] do_mount+0x19c/0x890
> [ 337.106989] [<ffffffff810e8456>] ? memdup_user+0x46/0x90
> [ 337.108572] [<ffffffff810e84f3>] ? strndup_user+0x53/0x70
> [ 337.110114] [<ffffffff811383fb>] sys_mount+0x8b/0xe0
> [ 337.111617] [<ffffffff816ed93b>] system_call_fastpath+0x16/0x1b
> [ 337.113133] Code: 38 c2 74 0f 66 0f 1f 44 00 00 f3 90 0f b6 03 38 c2 75 f7 48 83 c4 08 5b 5d c3 0f 1f 84 00 00 00 00 00 55 b8 00 01 00 00 48 89 e5 <f0> 66 0f c1 07 0f b6 d4 38 c2 74 0c 0f 1f 00 f3 90 0f b6 07 38
> [ 337.116588] RIP [<ffffffff816e6539>] _raw_spin_lock+0x9/0x30
> [ 337.118260] RSP <ffff8800b1d11ae8>
> [ 337.119998] CR2: 0000000000000024
> [ 337.188701] ---[ end trace c36d790becac1615 ]---
>
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
>
> diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
> index 85fe655..7229fd0 100644
> --- a/fs/ext3/inode.c
> +++ b/fs/ext3/inode.c
> @@ -225,6 +225,7 @@ void ext3_evict_inode (struct inode *inode)
> * use page cache.
> */
> if (inode->i_nlink && ext3_should_journal_data(inode) &&
> + EXT3_SB(inode->i_sb)->s_journal &&
> (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode))) {
> tid_t commit_tid = atomic_read(&ei->i_datasync_tid);
> journal_t *journal = EXT3_SB(inode->i_sb)->s_journal;
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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