Thread (3 messages) flat view 3 messages, 2 authors, 2025-10-28

Re: [PATCH net v2] sctp: Prevent TOCTOU out-of-bounds write

From: Kuniyuki Iwashima <kuniyu@google.com>
Date: 2025-10-27 17:51:54
Also in: linux-sctp, lkml

Thanks for the patch.

On Mon, Oct 27, 2025 at 3:16 AM Stefan Wiehler [off-list ref] wrote:
Make sure not to exceed bounds in case the address list has grown
between buffer allocation (time-of-check) and write (time-of-use).
Could you elaborate a bit more context here like which path
we don't hold lock_sock() as Xin confirmed in this thread ?

https://lore.kernel.org/netdev/CADvbK_ddE0oUPXijkFJbWF6tFTq5TntpFMzDWH+uV_kc+KB7VA@mail.gmail.com/ (local)

Also, it would be better to post the two patches as a series

git send-email --annotate --cover-letter --thread --no-chain-reply-to \
--subject-prefix "PATCH v3 net" \
--to ...

quoted hunk ↗ jump to hunk
Suggested-by: Kuniyuki Iwashima <kuniyu@google.com>
Fixes: 8f840e47f190 ("sctp: add the sctp_diag.c file")
Signed-off-by: Stefan Wiehler <redacted>
---
V1 -> V2: Add changelog and credit
---
 net/sctp/diag.c | 3 +++
 1 file changed, 3 insertions(+)
diff --git a/net/sctp/diag.c b/net/sctp/diag.c
index 996c2018f0e6..4ee44e0111ae 100644
--- a/net/sctp/diag.c
+++ b/net/sctp/diag.c
@@ -85,6 +85,9 @@ static int inet_diag_msg_sctpladdrs_fill(struct sk_buff *skb,
                memcpy(info, &laddr->a, sizeof(laddr->a));
                memset(info + sizeof(laddr->a), 0, addrlen - sizeof(laddr->a));
                info += addrlen;
+
+               if (!--addrcnt)
+                       break;
        }

        return 0;
--
2.51.0
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