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authorEryu Guan <guaneryu@gmail.com>2016-03-12 21:40:32 -0500
committerTheodore Ts'o <tytso@mit.edu>2016-03-12 21:40:32 -0500
commit5e1021f2b6dff1a86a468a1424d59faae2bc63c1 (patch)
tree13e630a594399bdbcd73b887731aff73bd7ded0d /fs/ext4
parenta8ed9b8695065d37d45efc446efbde5654f9f7c2 (diff)
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ext4: fix NULL pointer dereference in ext4_mark_inode_dirty()
ext4_reserve_inode_write() in ext4_mark_inode_dirty() could fail on error (e.g. EIO) and iloc.bh can be NULL in this case. But the error is ignored in the following "if" condition and ext4_expand_extra_isize() might be called with NULL iloc.bh set, which triggers NULL pointer dereference. This is uncovered by commit 8b4953e13f4c ("ext4: reserve code points for the project quota feature"), which enlarges the ext4_inode size, and run the following script on new kernel but with old mke2fs: #/bin/bash mnt=/mnt/ext4 devname=ext4-error dev=/dev/mapper/$devname fsimg=/home/fs.img trap cleanup 0 1 2 3 9 15 cleanup() { umount $mnt >/dev/null 2>&1 dmsetup remove $devname losetup -d $backend_dev rm -f $fsimg exit 0 } rm -f $fsimg fallocate -l 1g $fsimg backend_dev=`losetup -f --show $fsimg` devsize=`blockdev --getsz $backend_dev` good_tab="0 $devsize linear $backend_dev 0" error_tab="0 $devsize error $backend_dev 0" dmsetup create $devname --table "$good_tab" mkfs -t ext4 $dev mount -t ext4 -o errors=continue,strictatime $dev $mnt dmsetup load $devname --table "$error_tab" && dmsetup resume $devname echo 3 > /proc/sys/vm/drop_caches ls -l $mnt exit 0 [ Patch changed to simplify the function a tiny bit. -- Ted ] Signed-off-by: Eryu Guan <guaneryu@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/inode.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index ce2c4c62386f..b41432efcc09 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5312,6 +5312,8 @@ int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
might_sleep();
trace_ext4_mark_inode_dirty(inode, _RET_IP_);
err = ext4_reserve_inode_write(handle, inode, &iloc);
+ if (err)
+ return err;
if (ext4_handle_valid(handle) &&
EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize &&
!ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND)) {
@@ -5342,9 +5344,7 @@ int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
}
}
}
- if (!err)
- err = ext4_mark_iloc_dirty(handle, inode, &iloc);
- return err;
+ return ext4_mark_iloc_dirty(handle, inode, &iloc);
}
/*