From 7925f4fb3d8b5b0c1bb9c5ded85078197c6f87af Mon Sep 17 00:00:00 2001 From: Eryu Guan Date: Sat, 12 Mar 2016 21:40:32 -0500 Subject: ext4: fix NULL pointer dereference in ext4_mark_inode_dirty() [ Upstream commit 5e1021f2b6dff1a86a468a1424d59faae2bc63c1 ] 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 Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin --- fs/ext4/inode.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'fs') diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index f43996884242..ba12e2953aec 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5094,6 +5094,8 @@ 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)) { @@ -5124,9 +5126,7 @@ 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); } /* -- cgit v1.2.3