ext4_check_dir_entry() currently does not catch a case when a directory entry ends so close to the block end that the header of the next directory entry would not fit in the remaining space. This can lead to directory iteration code trying to access address beyond end of current buffer head leading to oops.

CC: stable@vger.kernel.org Signed-off-by: Jan Kara jack@suse.cz --- fs/ext4/dir.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c index 9fdd2b269d61..6305d5ec25af 100644 --- a/fs/ext4/dir.c +++ b/fs/ext4/dir.c @@ -81,6 +81,11 @@ int __ext4_check_dir_entry(const char *function, unsigned int line, error_msg = "rec_len is too small for name_len"; else if (unlikely(((char *) de - buf) + rlen > size)) error_msg = "directory entry overrun"; + else if (unlikely(((char *) de - buf) + rlen > + size - EXT4_DIR_REC_LEN(1) && + ((char *) de - buf) + rlen != size)) { + error_msg = "directory entry too close to block end"; + } 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";