From ecebf55d27a11538ea84aee0be643dd953f830d5 Mon Sep 17 00:00:00 2001 From: Pan Bian Date: Sun, 25 Nov 2018 08:58:02 +0800 Subject: [PATCH] ext2: fix potential use after free 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 Signed-off-by: Jan Kara --- fs/ext2/xattr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c index 62d9a659a8ff..dd8f10db82e9 100644 --- a/fs/ext2/xattr.c +++ b/fs/ext2/xattr.c @@ -612,9 +612,9 @@ skip_replace: } cleanup: - brelse(bh); if (!(bh && header == HDR(bh))) kfree(header); + brelse(bh); up_write(&EXT2_I(inode)->xattr_sem); return error;