[PATCH 6.6 02/16] ocfs2: add bounds checking to ocfs2_check_dir_entry()

Greg Kroah-Hartman
2024-07-25T14:45:08Z

From: lei lu <llfamsec@gmail.com>

commit 255547c6bb8940a97eea94ef9d464ea5967763fb upstream.

This adds sanity checks for ocfs2_dir_entry to make sure all members of
ocfs2_dir_entry don't stray beyond valid memory region.

Link: https://lkml.kernel.org/r/20240626104433.163270-1-llfamsec@gmail.com
Signed-off-by: lei lu <llfamsec@gmail.com>
Reviewed-by: Heming Zhao <heming.zhao@suse.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ocfs2/dir.c | 46 +++++++++++++++++++++++++++++-----------------
1 file changed, 29 insertions(+), 17 deletions(-)

--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -294,13 +294,16 @@ out:
* bh passed here can be an inode block or a dir data block, depending
* on the inode inline data flag.
*/
-static int ocfs2_check_dir_entry(struct inode * dir,
- struct ocfs2_dir_entry * de,
- struct buffer_head * bh,
+static int ocfs2_check_dir_entry(struct inode *dir,
+ struct ocfs2_dir_entry *de,
+ struct buffer_head *bh,
+ char *buf,
+ unsigned int size,
unsigned long offset)
{
const char *error_msg = NULL;
const int rlen = le16_to_cpu(de->rec_len);
+ const unsigned long next_offset = ((char *) de - buf) + rlen;

if (unlikely(rlen < OCFS2_DIR_REC_LEN(1)))
error_msg = "rec_len is smaller than minimal";
@@ -308,9 +311,11 @@ static int ocfs2_check_dir_entry(struct
error_msg = "rec_len % 4 != 0";
else if (unlikely(rlen < OCFS2_DIR_REC_LEN(de->name_len)))
error_msg = "rec_len is too small for name_len";
- else if (unlikely(
- ((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize))
- error_msg = "directory entry across blocks";
+ else if (unlikely(next_offset > size))
+ error_msg = "directory entry overrun";
+ else if (unlikely(next_offset > size - OCFS2_DIR_REC_LEN(1)) &&
+ next_offset != size)
+ error_msg = "directory entry too close to end";

if (unlikely(error_msg != NULL))
mlog(ML_ERROR, "bad entry in directory #%llu: %s - "
@@ -352,16 +357,17 @@ static inline int ocfs2_search_dirblock(
de_buf = first_de;
dlimit = de_buf + bytes;

- while (de_buf < dlimit) {
+ while (de_buf < dlimit - OCFS2_DIR_MEMBER_LEN) {
/* this code is executed quadratically often */
/* do minimal checking `by hand' */

de = (struct ocfs2_dir_entry *) de_buf;

- if (de_buf + namelen <= dlimit &&
+ if (de->name + namelen <= dlimit &&
ocfs2_match(namelen, name, de)) {
/* found a match - just to be sure, do a full check */
- if (!ocfs2_check_dir_entry(dir, de, bh, offset)) {
+ if (!ocfs2_check_dir_entry(dir, de, bh, first_de,
+ bytes, offset)) {
ret = -1;
goto bail;
}
@@ -1138,7 +1144,7 @@ static int __ocfs2_delete_entry(handle_t
pde = NULL;
de = (struct ocfs2_dir_entry *) first_de;
while (i < bytes) {
- if (!ocfs2_check_dir_entry(dir, de, bh, i)) {
+ if (!ocfs2_check_dir_entry(dir, de, bh, first_de, bytes, i)) {
status = -EIO;
mlog_errno(status);
goto bail;
@@ -1638,7 +1644,8 @@ int __ocfs2_add_entry(handle_t *handle,
/* These checks should've already been passed by the
* prepare function, but I guess we can leave them
* here anyway. */
- if (!ocfs2_check_dir_entry(dir, de, insert_bh, offset)) {
+ if (!ocfs2_check_dir_entry(dir, de, insert_bh, data_start,
+ size, offset)) {
retval = -ENOENT;
goto bail;
}
@@ -1777,7 +1784,8 @@ static int ocfs2_dir_foreach_blk_id(stru
}

de = (struct ocfs2_dir_entry *) (data->id_data + ctx->pos);
- if (!ocfs2_check_dir_entry(inode, de, di_bh, ctx->pos)) {
+ if (!ocfs2_check_dir_entry(inode, de, di_bh, (char *)data->id_data,
+ i_size_read(inode), ctx->pos)) {
/* On error, skip the f_pos to the end. */
ctx->pos = i_size_read(inode);
break;
@@ -1870,7 +1878,8 @@ static int ocfs2_dir_foreach_blk_el(stru
while (ctx->pos < i_size_read(inode)
&& offset < sb->s_blocksize) {
de = (struct ocfs2_dir_entry *) (bh->b_data + offset);
- if (!ocfs2_check_dir_entry(inode, de, bh, offset)) {
+ if (!ocfs2_check_dir_entry(inode, de, bh, bh->b_data,
+ sb->s_blocksize, offset)) {
/* On error, skip the f_pos to the
next block. */
ctx->pos = (ctx->pos | (sb->s_blocksize - 1)) + 1;
@@ -3342,7 +3351,7 @@ static int ocfs2_find_dir_space_id(struc
struct super_block *sb = dir->i_sb;
struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
struct ocfs2_dir_entry *de, *last_de = NULL;
- char *de_buf, *limit;
+ char *first_de, *de_buf, *limit;
unsigned long offset = 0;
unsigned int rec_len, new_rec_len, free_space;

@@ -3355,14 +3364,16 @@ static int ocfs2_find_dir_space_id(struc
else
free_space = dir->i_sb->s_blocksize - i_size_read(dir);

- de_buf = di->id2.i_data.id_data;
+ first_de = di->id2.i_data.id_data;
+ de_buf = first_de;
limit = de_buf + i_size_read(dir);
rec_len = OCFS2_DIR_REC_LEN(namelen);

while (de_buf < limit) {
de = (struct ocfs2_dir_entry *)de_buf;

- if (!ocfs2_check_dir_entry(dir, de, di_bh, offset)) {
+ if (!ocfs2_check_dir_entry(dir, de, di_bh, first_de,
+ i_size_read(dir), offset)) {
ret = -ENOENT;
goto out;
}
@@ -3444,7 +3455,8 @@ static int ocfs2_find_dir_space_el(struc
/* move to next block */
de = (struct ocfs2_dir_entry *) bh->b_data;
}
- if (!ocfs2_check_dir_entry(dir, de, bh, offset)) {
+ if (!ocfs2_check_dir_entry(dir, de, bh, bh->b_data, blocksize,
+ offset)) {
status = -ENOENT;
goto bail;
}