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authorLuís Henriques <lhenriques@suse.de>2022-10-12 14:13:30 +0100
committerTheodore Ts'o <tytso@mit.edu>2022-11-06 01:07:49 -0400
commit17a0bc9bd697f75cfdf9b378d5eb2d7409c91340 (patch)
tree1170b3ffacf9685e14a97b6301776d2e4d2e2764 /fs
parent9a8c5b0d061554fedd7dbe894e63aa34d0bac7c4 (diff)
ext4: fix BUG_ON() when directory entry has invalid rec_len
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@kernel.org Link: https://bugzilla.kernel.org/show_bug.cgi?id=216540 Signed-off-by: Luís Henriques <lhenriques@suse.de> Link: https://lore.kernel.org/r/20221012131330.32456-1-lhenriques@suse.de Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs')
-rw-r--r--fs/ext4/namei.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 4183a4cb4a21..be8136aafa22 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2259,8 +2259,16 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
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);