3.16.62-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o <tytso@xxxxxxx> commit 4d982e25d0bdc83d8c64e66fdeca0b89240b3b85 upstream. 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 <tytso@xxxxxxx> Reported-by: Wen Xu <wen.xu@xxxxxxxxxx> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- fs/ext4/dir.c | 20 +++++++++----------- fs/ext4/inline.c | 4 +++- 2 files changed, 12 insertions(+), 12 deletions(-) --- a/fs/ext4/dir.c +++ b/fs/ext4/dir.c @@ -77,7 +77,7 @@ int __ext4_check_dir_entry(const char *f else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len))) error_msg = "rec_len is too small for name_len"; else if (unlikely(((char *) de - buf) + rlen > size)) - error_msg = "directory entry across range"; + error_msg = "directory entry overrun"; else if (unlikely(le32_to_cpu(de->inode) > le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count))) error_msg = "inode out of bounds"; @@ -86,18 +86,16 @@ int __ext4_check_dir_entry(const char *f if (filp) ext4_error_file(filp, function, line, bh->b_blocknr, - "bad entry in directory: %s - offset=%u(%u), " - "inode=%u, rec_len=%d, name_len=%d", - error_msg, (unsigned) (offset % size), - offset, le32_to_cpu(de->inode), - rlen, de->name_len); + "bad entry in directory: %s - offset=%u, " + "inode=%u, rec_len=%d, name_len=%d, size=%d", + error_msg, offset, le32_to_cpu(de->inode), + rlen, de->name_len, size); else ext4_error_inode(dir, function, line, bh->b_blocknr, - "bad entry in directory: %s - offset=%u(%u), " - "inode=%u, rec_len=%d, name_len=%d", - error_msg, (unsigned) (offset % size), - offset, le32_to_cpu(de->inode), - rlen, de->name_len); + "bad entry in directory: %s - offset=%u, " + "inode=%u, rec_len=%d, name_len=%d, size=%d", + error_msg, offset, le32_to_cpu(de->inode), + rlen, de->name_len, size); return 1; } --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -1741,6 +1741,7 @@ int empty_inline_dir(struct inode *dir, { int err, inline_size; struct ext4_iloc iloc; + size_t inline_len; void *inline_pos; unsigned int offset; struct ext4_dir_entry_2 *de; @@ -1768,8 +1769,9 @@ int empty_inline_dir(struct inode *dir, 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,
