From: Pavel Shilovsky <pshilovsky@xxxxxxxxx>
During following a symbolic link we received err_buf from SMB2_open().
While the validity of SMB2 error response is checked previously
in smb2_check_message() a symbolic link payload is not checked at all.
Fix it by adding such checks.
Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Pavel Shilovsky <pshilovsky@xxxxxxxxx>
---
fs/cifs/smb2ops.c | 30 +++++++++++++++++++++++++++++-
1 file changed, 29 insertions(+), 1 deletion(-)
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 527d1ac..9ec025c 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -1044,6 +1044,9 @@ smb2_new_lease_key(struct cifs_fid *fid)
get_random_bytes(fid->lease_key, SMB2_LEASE_KEY_SIZE);
}
+#define SMB2_SYMLINK_STRUCT_SIZE \
+ (sizeof(struct smb2_err_rsp) - 1 + sizeof(struct smb2_symlink_err_rsp))
+
static int
smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
const char *full_path, char **target_path,
@@ -1056,7 +1059,10 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
struct cifs_fid fid;
struct smb2_err_rsp *err_buf = NULL;
struct smb2_symlink_err_rsp *symlink;
- unsigned int sub_len, sub_offset;
+ unsigned int sub_len;
+ unsigned int sub_offset;
+ unsigned int print_len;
+ unsigned int print_offset;
cifs_dbg(FYI, "%s: path: %s\n", __func__, full_path);
@@ -1077,11 +1083,33 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
kfree(utf16_path);
return -ENOENT;
}
+
+ if (err_buf->ByteCount < sizeof(struct smb2_symlink_err_rsp) ||
+ get_rfc1002_length(err_buf) + 4 < SMB2_SYMLINK_STRUCT_SIZE) {
+ kfree(utf16_path);
+ return -ENOENT;
+ }
+
/* open must fail on symlink - reset rc */
rc = 0;
symlink = (struct smb2_symlink_err_rsp *)err_buf->ErrorData;
sub_len = le16_to_cpu(symlink->SubstituteNameLength);
sub_offset = le16_to_cpu(symlink->SubstituteNameOffset);
+ print_len = le16_to_cpu(symlink->PrintNameLength);
+ print_offset = le16_to_cpu(symlink->PrintNameOffset);
+
+ if (get_rfc1002_length(err_buf) + 4 <
+ SMB2_SYMLINK_STRUCT_SIZE + sub_offset + sub_len) {
+ kfree(utf16_path);
+ return -ENOENT;
+ }
+
+ if (get_rfc1002_length(err_buf) + 4 <
+ SMB2_SYMLINK_STRUCT_SIZE + print_offset + print_len) {
+ kfree(utf16_path);
+ return -ENOENT;
+ }
+
*target_path = cifs_strndup_from_utf16(
(char *)symlink->PathBuffer + sub_offset,
sub_len, true, cifs_sb->local_nls);
--
2.1.4
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