Wind River Support Network

Description

In the Linux kernel, the following vulnerability has been resolved:  ksmbd: validate response sizes in ipc_validate_msg()  ipc_validate_msg() computes the expected message size for each response type by adding (or multiplying) attacker-controlled fields from the daemon response to a fixed struct size in unsigned int arithmetic.  Three cases can overflow:    KSMBD_EVENT_RPC_REQUEST:       msg_sz = sizeof(struct ksmbd_rpc_command) + resp->payload_sz;   KSMBD_EVENT_SHARE_CONFIG_REQUEST:       msg_sz = sizeof(struct ksmbd_share_config_response) +                resp->payload_sz;   KSMBD_EVENT_LOGIN_REQUEST_EXT:       msg_sz = sizeof(struct ksmbd_login_response_ext) +                resp->ngroups * sizeof(gid_t);  resp->payload_sz is __u32 and resp->ngroups is __s32.  Each addition can wrap in unsigned int; the multiplication by sizeof(gid_t) mixes signed and size_t, so a negative ngroups is converted to SIZE_MAX before the multiply.  A wrapped value of msg_sz that happens to equal entry->msg_sz bypasses the size check on the next line, and downstream consumers (smb2pdu.c:6742 memcpy using rpc_resp->payload_sz, kmemdup in ksmbd_alloc_user using resp_ext->ngroups) then trust the unverified length.  Use check_add_overflow() on the RPC_REQUEST and SHARE_CONFIG_REQUEST paths to detect integer overflow without constraining functional payload size; userspace ksmbd-tools grows NDR responses in 4096-byte chunks for calls like NetShareEnumAll, so a hard transport cap is unworkable on the response side.  For LOGIN_REQUEST_EXT, reject resp->ngroups outside the signed [0, NGROUPS_MAX] range up front and report the error from ipc_validate_msg() so it fires at the IPC boundary; with that bound the subsequent multiplication and addition stay well below UINT_MAX.  The now-redundant ngroups check and pr_err in ksmbd_alloc_user() are removed.  This is the response-side analogue of aab98e2dbd64 ("ksmbd: fix integer overflows on 32 bit systems"), which hardened the request side.