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authorTheodore Ts'o <tytso@mit.edu>2009-01-16 11:13:40 -0500
committerTheodore Ts'o <tytso@mit.edu>2009-01-16 11:13:40 -0500
commite6b8bc09ba2075cd91fbffefcd2778b1a00bd76f (patch)
tree07a439d21576794c5d39a06a86b09e690e55f2f2 /fs/ext4
parent06a279d636734da32bb62dd2f7b0ade666f65d7c (diff)
ext4: Add sanity check to make_indexed_dir
Make sure the rec_len field in the '..' entry is sane, lest we overrun the directory block and cause a kernel oops on a purposefully corrupted filesystem. Thanks to Sami Liedes for reporting this bug. http://bugzilla.kernel.org/show_bug.cgi?id=12430 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/namei.c21
1 files changed, 15 insertions, 6 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index fec0b4c2f5f1..ba702bd7910d 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1368,7 +1368,7 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry,
1368 struct fake_dirent *fde; 1368 struct fake_dirent *fde;
1369 1369
1370 blocksize = dir->i_sb->s_blocksize; 1370 blocksize = dir->i_sb->s_blocksize;
1371 dxtrace(printk(KERN_DEBUG "Creating index\n")); 1371 dxtrace(printk(KERN_DEBUG "Creating index: inode %lu\n", dir->i_ino));
1372 retval = ext4_journal_get_write_access(handle, bh); 1372 retval = ext4_journal_get_write_access(handle, bh);
1373 if (retval) { 1373 if (retval) {
1374 ext4_std_error(dir->i_sb, retval); 1374 ext4_std_error(dir->i_sb, retval);
@@ -1377,6 +1377,20 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry,
1377 } 1377 }
1378 root = (struct dx_root *) bh->b_data; 1378 root = (struct dx_root *) bh->b_data;
1379 1379
1380 /* The 0th block becomes the root, move the dirents out */
1381 fde = &root->dotdot;
1382 de = (struct ext4_dir_entry_2 *)((char *)fde +
1383 ext4_rec_len_from_disk(fde->rec_len));
1384 if ((char *) de >= (((char *) root) + blocksize)) {
1385 ext4_error(dir->i_sb, __func__,
1386 "invalid rec_len for '..' in inode %lu",
1387 dir->i_ino);
1388 brelse(bh);
1389 return -EIO;
1390 }
1391 len = ((char *) root) + blocksize - (char *) de;
1392
1393 /* Allocate new block for the 0th block's dirents */
1380 bh2 = ext4_append(handle, dir, &block, &retval); 1394 bh2 = ext4_append(handle, dir, &block, &retval);
1381 if (!(bh2)) { 1395 if (!(bh2)) {
1382 brelse(bh); 1396 brelse(bh);
@@ -1385,11 +1399,6 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry,
1385 EXT4_I(dir)->i_flags |= EXT4_INDEX_FL; 1399 EXT4_I(dir)->i_flags |= EXT4_INDEX_FL;
1386 data1 = bh2->b_data; 1400 data1 = bh2->b_data;
1387 1401
1388 /* The 0th block becomes the root, move the dirents out */
1389 fde = &root->dotdot;
1390 de = (struct ext4_dir_entry_2 *)((char *)fde +
1391 ext4_rec_len_from_disk(fde->rec_len));
1392 len = ((char *) root) + blocksize - (char *) de;
1393 memcpy (data1, de, len); 1402 memcpy (data1, de, len);
1394 de = (struct ext4_dir_entry_2 *) data1; 1403 de = (struct ext4_dir_entry_2 *) data1;
1395 top = data1 + len; 1404 top = data1 + len;