From 4d982e25d0bdc83d8c64e66fdeca0b89240b3b85 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Mon, 27 Aug 2018 09:22:45 -0400 Subject: ext4: avoid divide by zero fault when deleting corrupted inline directories A specially crafted file system can trick empty_inline_dir() into reading past the last valid entry in a inline directory, and then run into the end of xattr marker. This will trigger a divide by zero fault. Fix this by using the size of the inline directory instead of dir->i_size. Also clean up error reporting in __ext4_check_dir_entry so that the message is clearer and more understandable --- and avoids the division by zero trap if the size passed in is zero. (I'm not sure why we coded it that way in the first place; printing offset % size is actually more confusing and less useful.) https://bugzilla.kernel.org/show_bug.cgi?id=200933 Signed-off-by: Theodore Ts'o Reported-by: Wen Xu Cc: stable@vger.kernel.org --- fs/ext4/inline.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'fs/ext4/inline.c') diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c index 3543fe80a3c4..7b4736022761 100644 --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -1753,6 +1753,7 @@ bool empty_inline_dir(struct inode *dir, int *has_inline_data) { int err, inline_size; struct ext4_iloc iloc; + size_t inline_len; void *inline_pos; unsigned int offset; struct ext4_dir_entry_2 *de; @@ -1780,8 +1781,9 @@ bool empty_inline_dir(struct inode *dir, int *has_inline_data) goto out; } + inline_len = ext4_get_inline_size(dir); offset = EXT4_INLINE_DOTDOT_SIZE; - while (offset < dir->i_size) { + while (offset < inline_len) { de = ext4_get_inline_entry(dir, &iloc, offset, &inline_pos, &inline_size); if (ext4_check_dir_entry(dir, NULL, de, -- cgit v1.2.3