RE: [PATCH net] tipc: fix integer overflow in tipc_recvmsg() and tipc_recvstream()

[Tung Quang Nguyen]

>Subject: [PATCH net] tipc: fix integer overflow in tipc_recvmsg() and
>tipc_recvstream()
>
>In tipc_recvmsg(), the copy length is computed as:
>
>  copy = min_t(int, dlen - offset, buflen);
>
>buflen is size_t but min_t(int, ...) casts it to int. When buflen exceeds INT_MAX
>(e.g. 0xFFFFFFFF via io_uring provided buffers), it wraps negative, wins the
>comparison, and the negative copy length propagates to simple_copy_to_iter()
>where int-to-size_t promotion makes it SIZE_MAX, triggering a WARN_ON.
>tipc_recvstream() has the same pattern.
>
>  Kernel panic - not syncing: kernel: panic_on_warn set ...
>  RIP: 0010:simple_copy_to_iter+0x9e/0xd0 (net/core/datagram.c:521)
>  Call Trace:
>   __skb_datagram_iter+0x123/0x8b0 (net/core/datagram.c:402)
>   skb_copy_datagram_iter+0x77/0x1a0 (net/core/datagram.c:534)
>   tipc_recvmsg+0x3d7/0xe80 (net/tipc/socket.c:1934)
>   io_recvmsg+0x47e/0xda0
>
>Fix by changing min_t(int, ...) to min_t(size_t, ...) in both functions. The result is
>always <= (dlen - offset), which is bounded by TIPC maximum message size
>(0x1ffff bytes), so the implicit narrowing on assignment to int copy is always
>safe.
>
>Fixes: e9f8b10101c6 ("tipc: refactor function tipc_sk_recvmsg()")
>Fixes: ec8a09fbbeff ("tipc: refactor function tipc_sk_recv_stream()")
>Reported-by: AutonomousCodeSecurity@xxxxxxxxxxxxx
>Signed-off-by: Cen Zhang (Microsoft) <blbllhy@xxxxxxxxx>
>---

Reviewed-by: Tung Nguyen <tung.quang.nguyen@xxxxxxxx>