This is a note to let you know that I've just added the patch titled
ext4: fix BUG_ON() when directory entry has invalid rec_len
to the 6.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-fix-bug_on-when-directory-entry-has-invalid-rec_len.patch
and it can be found in the queue-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 17a0bc9bd697f75cfdf9b378d5eb2d7409c91340 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lu=C3=ADs=20Henriques?= <lhenriques@xxxxxxx>
Date: Wed, 12 Oct 2022 14:13:30 +0100
Subject: ext4: fix BUG_ON() when directory entry has invalid rec_len
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From: Luís Henriques <lhenriques@xxxxxxx>
commit 17a0bc9bd697f75cfdf9b378d5eb2d7409c91340 upstream.
The rec_len field in the directory entry has to be a multiple of 4. A
corrupted filesystem image can be used to hit a BUG() in
ext4_rec_len_to_disk(), called from make_indexed_dir().
------------[ cut here ]------------
kernel BUG at fs/ext4/ext4.h:2413!
...
RIP: 0010:make_indexed_dir+0x53f/0x5f0
...
Call Trace:
<TASK>
? add_dirent_to_buf+0x1b2/0x200
ext4_add_entry+0x36e/0x480
ext4_add_nondir+0x2b/0xc0
ext4_create+0x163/0x200
path_openat+0x635/0xe90
do_filp_open+0xb4/0x160
? __create_object.isra.0+0x1de/0x3b0
? _raw_spin_unlock+0x12/0x30
do_sys_openat2+0x91/0x150
__x64_sys_open+0x6c/0xa0
do_syscall_64+0x3c/0x80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
The fix simply adds a call to ext4_check_dir_entry() to validate the
directory entry, returning -EFSCORRUPTED if the entry is invalid.
CC: stable@xxxxxxxxxx
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216540
Signed-off-by: Luís Henriques <lhenriques@xxxxxxx>
Link: https://lore.kernel.org/r/20221012131330.32456-1-lhenriques@xxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ext4/namei.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2259,8 +2259,16 @@ static int make_indexed_dir(handle_t *ha
memset(de, 0, len); /* wipe old data */
de = (struct ext4_dir_entry_2 *) data2;
top = data2 + len;
- while ((char *)(de2 = ext4_next_entry(de, blocksize)) < top)
+ while ((char *)(de2 = ext4_next_entry(de, blocksize)) < top) {
+ if (ext4_check_dir_entry(dir, NULL, de, bh2, data2, len,
+ (data2 + (blocksize - csum_size) -
+ (char *) de))) {
+ brelse(bh2);
+ brelse(bh);
+ return -EFSCORRUPTED;
+ }
de = de2;
+ }
de->rec_len = ext4_rec_len_to_disk(data2 + (blocksize - csum_size) -
(char *) de, blocksize);
Patches currently in stable-queue which might be from lhenriques@xxxxxxx are
queue-6.0/ext4-fix-bug_on-when-directory-entry-has-invalid-rec_len.patch
