From: Jeffle Xu jefflexu@linux.alibaba.com
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@linux.alibaba.com Reviewed-by: Joseph Qi joseph.qi@linux.alibaba.com Cc: stable@kernel.org # 2.6.19 Reviewed-by: Ritesh Harjani riteshh@linux.ibm.com Reviewed-by: Jan Kara jack@suse.cz Link: https://lore.kernel.org/r/1587628004-95123-1-git-send-email-jefflexu@linux.a... Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/ext4/xattr.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
--- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -1800,8 +1800,11 @@ 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));