4.9-stable review patch. If anyone has any objections, please let me know.
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From: Pan Bian bianpan2016@163.com
commit ecebf55d27a11538ea84aee0be643dd953f830d5 upstream.
The function ext2_xattr_set calls brelse(bh) to drop the reference count of bh. After that, bh may be freed. However, following brelse(bh), it reads bh->b_data via macro HDR(bh). This may result in a use-after-free bug. This patch moves brelse(bh) after reading field.
CC: stable@vger.kernel.org Signed-off-by: Pan Bian bianpan2016@163.com Signed-off-by: Jan Kara jack@suse.cz Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/ext2/xattr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/ext2/xattr.c +++ b/fs/ext2/xattr.c @@ -609,9 +609,9 @@ skip_replace: }
cleanup: - brelse(bh); if (!(bh && header == HDR(bh))) kfree(header); + brelse(bh); up_write(&EXT2_I(inode)->xattr_sem);
return error;