From: Jan Kara Date: Mon, 2 Dec 2019 17:02:13 +0000 (+0100) Subject: ext4: check for directory entries too close to block end X-Git-Tag: v3.16.83~125 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=29f18582b8db7453e361ac2e23e1a76cc0289b5b;p=thirdparty%2Fkernel%2Fstable.git ext4: check for directory entries too close to block end commit 109ba779d6cca2d519c5dd624a3276d03e21948e upstream. 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. Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20191202170213.4761-3-jack@suse.cz Signed-off-by: Theodore Ts'o Signed-off-by: Ben Hutchings --- diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c index 20e6a870d1147..4d17006a1b8e7 100644 --- a/fs/ext4/dir.c +++ b/fs/ext4/dir.c @@ -78,6 +78,11 @@ 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";