From 177af6102527571eaa381323dddd7084c203353e Mon Sep 17 00:00:00 2001 From: Qianchang Zhao Date: Wed, 22 Oct 2025 15:27:47 +0900 Subject: [PATCH] ksmbd: transport_ipc: validate payload size before reading handle 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 Signed-off-by: Qianchang Zhao Acked-by: Namjae Jeon Signed-off-by: Steve French --- fs/smb/server/transport_ipc.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/smb/server/transport_ipc.c b/fs/smb/server/transport_ipc.c index 46f87fd1ce1c..2c08cccfa680 100644 --- a/fs/smb/server/transport_ipc.c +++ b/fs/smb/server/transport_ipc.c @@ -263,10 +263,16 @@ static void ipc_msg_handle_free(int handle) static int handle_response(int type, void *payload, size_t sz) { - unsigned int handle = *(unsigned int *)payload; + unsigned int handle; struct ipc_msg_table_entry *entry; int ret = 0; + /* Prevent 4-byte read beyond declared payload size */ + if (sz < sizeof(unsigned int)) + return -EINVAL; + + handle = *(unsigned int *)payload; + ipc_update_last_active(); down_read(&ipc_msg_table_lock); hash_for_each_possible(ipc_msg_table, entry, ipc_table_hlist, handle) { -- 2.25.1