| Message ID | 1345211417-26968-1-git-send-email-tytso@mit.edu |
|---|---|
| State | Accepted, archived |
| Headers | show |
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index cd0c7ed..aabbb3f 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -2662,6 +2662,7 @@ cont: } path[0].p_depth = depth; path[0].p_hdr = ext_inode_hdr(inode); + i = 0; if (ext4_ext_check(inode, path[0].p_hdr, depth)) { err = -EIO;
Commit 968dee7722: "ext4: fix hole punch failure when depth is greater than 0" introduced a regression in v3.5.1/v3.6-rc1 which caused kernel crashes when users ran run "rm -rf" on large directory hierarchy on ext4 filesystems on RAID devices: BUG: unable to handle kernel NULL pointer dereference at 0000000000000028 Process rm (pid: 18229, threadinfo ffff8801276bc000, task ffff880123631710) Call Trace: [<ffffffff81236483>] ? __ext4_handle_dirty_metadata+0x83/0x110 [<ffffffff812353d3>] ext4_ext_truncate+0x193/0x1d0 [<ffffffff8120a8cf>] ? ext4_mark_inode_dirty+0x7f/0x1f0 [<ffffffff81207e05>] ext4_truncate+0xf5/0x100 [<ffffffff8120cd51>] ext4_evict_inode+0x461/0x490 [<ffffffff811a1312>] evict+0xa2/0x1a0 [<ffffffff811a1513>] iput+0x103/0x1f0 [<ffffffff81196d84>] do_unlinkat+0x154/0x1c0 [<ffffffff8118cc3a>] ? sys_newfstatat+0x2a/0x40 [<ffffffff81197b0b>] sys_unlinkat+0x1b/0x50 [<ffffffff816135e9>] system_call_fastpath+0x16/0x1b Code: 8b 4d 20 0f b7 41 02 48 8d 04 40 48 8d 04 81 49 89 45 18 0f b7 49 02 48 83 c1 01 49 89 4d 00 e9 ae f8 ff ff 0f 1f 00 49 8b 45 28 <48> 8b 40 28 49 89 45 20 e9 85 f8 ff ff 0f 1f 80 00 00 00 RIP [<ffffffff81233164>] ext4_ext_remove_space+0xa34/0xdf0 This could be reproduced as follows: The problem in commit 968dee7722 was that caused the variable 'i' to be left uninitialized if the truncate required more space than was available in the journal. This resulted in the function ext4_ext_truncate_extend_restart() returning -EAGAIN, which caused ext4_ext_remove_space() to restart the truncate operation after starting a new jbd2 handle. Reported-by: Maciej Żenczykowski <maze@google.com> Reported-by: Marti Raudsepp <marti@juffo.org> Tested-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@vger.kernel.org --- fs/ext4/extents.c | 1 + 1 file changed, 1 insertion(+)