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tipc: fix integer overflow in tipc_recvmsg() and tipc_recvstream()

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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: e9f8b10101 ("tipc: refactor function tipc_sk_recvmsg()")
Fixes: ec8a09fbbe ("tipc: refactor function tipc_sk_recv_stream()")
Reported-by: AutonomousCodeSecurity@microsoft.com
Signed-off-by: Cen Zhang (Microsoft) <blbllhy@gmail.com>
Reviewed-by: Tung Nguyen <tung.quang.nguyen@est.tech>
Link: https://patch.msgid.link/20260720214103.47732-1-blbllhy@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Cen Zhang (Microsoft) 2026-07-20 17:41:03 -04:00 committed by Jakub Kicinski
parent d73a2e81f3
commit 47f42ff521
1 changed files with 2 additions and 2 deletions
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4
net/tipc/socket.c
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@ -1936,7 +1936,7 @@ static int tipc_recvmsg(struct socket *sock, struct msghdr *m,
if (likely(!err)) {
int offset = skb_cb->bytes_read;
copy = min_t(int, dlen - offset, buflen);
copy = min_t(size_t, dlen - offset, buflen);
rc = skb_copy_datagram_msg(skb, hlen + offset, m, copy);
if (unlikely(rc))
goto exit;
@ -2068,7 +2068,7 @@ static int tipc_recvstream(struct socket *sock, struct msghdr *m,
/* Copy data if msg ok, otherwise return error/partial data */
if (likely(!err)) {
offset = skb_cb->bytes_read;
copy = min_t(int, dlen - offset, buflen - copied);
copy = min_t(size_t, dlen - offset, buflen - copied);
rc = skb_copy_datagram_msg(skb, hlen + offset, m, copy);
if (unlikely(rc))
break;