Messages in this thread Patch in this message | | | From | Fedor Pchelkin <> | Subject | [PATCH 1/1] udf: Fix null-ptr-deref in udf_write_fi() | Date | Sat, 7 Jan 2023 22:50:16 +0300 |
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udf_find_entry() can return NULL or an error pointer if it fails. So we should check its return value to avoid NULL pointer dereferencing in udf_write_fi() (which is called from udf_delete_entry()). Also, if udf_find_entry() returns an error pointer, it is possible that ofibh and ocfi structs hold invalid values which can cause additional problems in udf_write_fi().
If udf_find_entry() returns an error pointer, udf_rename() should return with an error code. If udf_find_entry() returns NULL, ofi has probably already been deleted.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Fixes: 231473f6ddce ("udf: Return error from udf_find_entry()") Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+8a5a459f324d510ea15a@syzkaller.appspotmail.com Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru> Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru> --- fs/udf/namei.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/udf/namei.c b/fs/udf/namei.c index 7c95c549dd64..6b058c6ebf93 100644 --- a/fs/udf/namei.c +++ b/fs/udf/namei.c @@ -1170,7 +1170,12 @@ static int udf_rename(struct user_namespace *mnt_userns, struct inode *old_dir, /* The old fid may have moved - find it again */ ofi = udf_find_entry(old_dir, &old_dentry->d_name, &ofibh, &ocfi); - udf_delete_entry(old_dir, ofi, &ofibh, &ocfi); + if (ofi && IS_ERR(ofi)) { + retval = PTR_ERR(ofi); + goto end_rename; + } else if (ofi) { + udf_delete_entry(old_dir, ofi, &ofibh, &ocfi); + } if (new_inode) { new_inode->i_ctime = current_time(new_inode); -- 2.34.1
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