handle_response() dereferences the payload as a 4-byte handle without verifying that the declared payload size is at least 4 bytes. A malformed or truncated message from ksmbd.mountd can lead to a 4-byte read past the declared payload size. Validate the size before dereferencing.

This is a minimal fix to guard the initial handle read.

Fixes: 0626e6641f6b ("cifsd: add server handler for central processing and tranport layers") Cc: stable@vger.kernel.org Reported-by: Qianchang Zhao pioooooooooip@gmail.com Signed-off-by: Qianchang Zhao pioooooooooip@gmail.com --- fs/smb/server/transport_ipc.c | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/fs/smb/server/transport_ipc.c b/fs/smb/server/transport_ipc.c index 46f87fd1ce1c..2028de4d3ddf 100644 --- a/fs/smb/server/transport_ipc.c +++ b/fs/smb/server/transport_ipc.c @@ -263,6 +263,10 @@ static void ipc_msg_handle_free(int handle)

static int handle_response(int type, void *payload, size_t sz) { + /* Prevent 4-byte read beyond declared payload size */ + if (sz < sizeof(unsigned int)) + return -EINVAL; + unsigned int handle = *(unsigned int *)payload; struct ipc_msg_table_entry *entry; int ret = 0;