[PATCH 4.19 09/84] f2fs: check memory boundary by insane namelen

Greg Kroah-Hartman
2020-01-16T23:28:45Z

From: Jaegeuk Kim <jaegeuk@kernel.org>

commit 4e240d1bab1ead280ddf5eb05058dba6bbd57d10 upstream.

If namelen is corrupted to have very long value, fill_dentries can copy
wrong memory area.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/f2fs/dir.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -806,6 +806,17 @@ int f2fs_fill_dentries(struct dir_contex
de_name.name = d->filename[bit_pos];
de_name.len = le16_to_cpu(de->name_len);

+ /* check memory boundary before moving forward */
+ bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
+ if (unlikely(bit_pos > d->max)) {
+ f2fs_msg(sbi->sb, KERN_WARNING,
+ "%s: corrupted namelen=%d, run fsck to fix.",
+ __func__, le16_to_cpu(de->name_len));
+ set_sbi_flag(sbi, SBI_NEED_FSCK);
+ err = -EINVAL;
+ goto out;
+ }
+
if (f2fs_encrypted_inode(d->inode)) {
int save_len = fstr->len;

@@ -826,7 +837,6 @@ int f2fs_fill_dentries(struct dir_contex
if (sbi->readdir_ra == 1)
f2fs_ra_node_page(sbi, le32_to_cpu(de->ino));

- bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
ctx->pos = start_pos + bit_pos;
}