This is a note to let you know that I've just added the patch titled
ext4: fix NULL pointer dereference in ext4_mark_inode_dirty()
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-fix-null-pointer-dereference-in-ext4_mark_inode_dirty.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5e1021f2b6dff1a86a468a1424d59faae2bc63c1 Mon Sep 17 00:00:00 2001
From: Eryu Guan <guaneryu@xxxxxxxxx>
Date: Sat, 12 Mar 2016 21:40:32 -0500
Subject: ext4: fix NULL pointer dereference in ext4_mark_inode_dirty()
From: Eryu Guan <guaneryu@xxxxxxxxx>
commit 5e1021f2b6dff1a86a468a1424d59faae2bc63c1 upstream.
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@xxxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ext4/inode.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5109,6 +5109,8 @@ int ext4_mark_inode_dirty(handle_t *hand
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)) {
@@ -5139,9 +5141,7 @@ int ext4_mark_inode_dirty(handle_t *hand
}
}
}
- if (!err)
- err = ext4_mark_iloc_dirty(handle, inode, &iloc);
- return err;
+ return ext4_mark_iloc_dirty(handle, inode, &iloc);
}
/*
Patches currently in stable-queue which might be from guaneryu@xxxxxxxxx are
queue-4.4/ext4-fix-null-pointer-dereference-in-ext4_mark_inode_dirty.patch
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