linux-kernel - [PATCH 4.4 086/137] ext4: check for directory entries too close to block end

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu,  2 Jan 2020 23:07:39 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jan Kara <jack@...e.cz>,
        Theodore Tso <tytso@....edu>
Subject: [PATCH 4.4 086/137] ext4: check for directory entries too close to block end

From: Jan Kara <jack@...e.cz>

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.

CC: stable@...r.kernel.org
Signed-off-by: Jan Kara <jack@...e.cz>
Link: https://lore.kernel.org/r/20191202170213.4761-3-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/ext4/dir.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -75,6 +75,11 @@ int __ext4_check_dir_entry(const char *f
 		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";