[PATCH 4.14 146/190] ext4: fix error pointer dereference
From: Greg Kroah-Hartman
Date: Fri Jun 19 2020 - 12:34:19 EST
From: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
commit 8418897f1bf87da0cb6936489d57a4320c32c0af upstream.
Don't pass error pointers to brelse().
commit 7159a986b420 ("ext4: fix some error pointer dereferences") has fixed
some cases, fix the remaining one case.
Once ext4_xattr_block_find()->ext4_sb_bread() failed, error pointer is
stored in @bs->bh, which will be passed to brelse() in the cleanup
routine of ext4_xattr_set_handle(). This will then cause a NULL panic
crash in __brelse().
BUG: unable to handle kernel NULL pointer dereference at 000000000000005b
RIP: 0010:__brelse+0x1b/0x50
Call Trace:
ext4_xattr_set_handle+0x163/0x5d0
ext4_xattr_set+0x95/0x110
__vfs_setxattr+0x6b/0x80
__vfs_setxattr_noperm+0x68/0x1b0
vfs_setxattr+0xa0/0xb0
setxattr+0x12c/0x1a0
path_setxattr+0x8d/0xc0
__x64_sys_setxattr+0x27/0x30
do_syscall_64+0x60/0x250
entry_SYSCALL_64_after_hwframe+0x49/0xbe
In this case, @bs->bh stores '-EIO' actually.
Fixes: fb265c9cb49e ("ext4: add ext4_sb_bread() to disambiguate ENOMEM cases")
Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
Reviewed-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxx # 2.6.19
Reviewed-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Link: https://lore.kernel.org/r/1587628004-95123-1-git-send-email-jefflexu@xxxxxxxxxxxxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ext4/xattr.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1823,8 +1823,11 @@ ext4_xattr_block_find(struct inode *inod
if (EXT4_I(inode)->i_file_acl) {
/* The inode already has an extended attribute block. */
bs->bh = ext4_sb_bread(sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
- if (IS_ERR(bs->bh))
- return PTR_ERR(bs->bh);
+ if (IS_ERR(bs->bh)) {
+ error = PTR_ERR(bs->bh);
+ bs->bh = NULL;
+ return error;
+ }
ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
atomic_read(&(bs->bh->b_count)),
le32_to_cpu(BHDR(bs->bh)->h_refcount));