| From 8418897f1bf87da0cb6936489d57a4320c32c0af Mon Sep 17 00:00:00 2001 |
| From: Jeffle Xu <jefflexu@linux.alibaba.com> |
| Date: Thu, 23 Apr 2020 15:46:44 +0800 |
| Subject: ext4: fix error pointer dereference |
| |
| 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.alibaba.com |
| 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 |
| @@ -1820,8 +1820,11 @@ 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)); |
