1 ext4: fix NULL pointer dereference in ext4_mark_inode_dirty()
3 From: Eryu Guan <guaneryu@gmail.com>
5 ext4_reserve_inode_write() in ext4_mark_inode_dirty() could fail on
6 error (e.g. EIO) and iloc.bh can be NULL in this case. But the error is
7 ignored in the following "if" condition and ext4_expand_extra_isize()
8 might be called with NULL iloc.bh set, which triggers NULL pointer
11 This is uncovered by commit 8b4953e13f4c ("ext4: reserve code points for
12 the project quota feature"), which enlarges the ext4_inode size, and
13 run the following script on new kernel but with old mke2fs:
18 dev=/dev/mapper/$devname
21 trap cleanup 0 1 2 3 9 15
25 umount $mnt >/dev/null 2>&1
26 dmsetup remove $devname
27 losetup -d $backend_dev
33 fallocate -l 1g $fsimg
34 backend_dev=`losetup -f --show $fsimg`
35 devsize=`blockdev --getsz $backend_dev`
37 good_tab="0 $devsize linear $backend_dev 0"
38 error_tab="0 $devsize error $backend_dev 0"
40 dmsetup create $devname --table "$good_tab"
43 mount -t ext4 -o errors=continue,strictatime $dev $mnt
45 dmsetup load $devname --table "$error_tab" && dmsetup resume $devname
46 echo 3 > /proc/sys/vm/drop_caches
50 [ Patch changed to simplify the function a tiny bit. -- Ted ]
52 Signed-off-by: Eryu Guan <guaneryu@gmail.com>
53 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
55 fs/ext4/inode.c | 6 +++---
56 1 file changed, 3 insertions(+), 3 deletions(-)
58 diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
59 index ce2c4c6..b41432e 100644
62 @@ -5312,6 +5312,8 @@ int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
64 trace_ext4_mark_inode_dirty(inode, _RET_IP_);
65 err = ext4_reserve_inode_write(handle, inode, &iloc);
68 if (ext4_handle_valid(handle) &&
69 EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize &&
70 !ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND)) {
71 @@ -5342,9 +5344,7 @@ int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
76 - err = ext4_mark_iloc_dirty(handle, inode, &iloc);
78 + return ext4_mark_iloc_dirty(handle, inode, &iloc);