From: Nate Karstens Date: Thu, 6 Nov 2025 22:28:33 +0000 (-0600) Subject: strparser: Fix signed/unsigned mismatch bug X-Git-Tag: v6.18-rc6~31^2~27 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4da4e4bde1c453ac5cc2dce5def81d504ae257ee;p=thirdparty%2Fkernel%2Flinux.git strparser: Fix signed/unsigned mismatch bug The `len` member of the sk_buff is an unsigned int. This is cast to `ssize_t` (a signed type) for the first sk_buff in the comparison, but not the second sk_buff. On 32-bit systems, this can result in an integer underflow for certain values because unsigned arithmetic is being used. This appears to be an oversight: if the intention was to use unsigned arithmetic, then the first cast would have been omitted. The change ensures both len values are cast to `ssize_t`. The underflow causes an issue with ktls when multiple TLS PDUs are included in a single TCP segment. The mainline kernel does not use strparser for ktls anymore, but this is still useful for other features that still use strparser, and for backporting. Signed-off-by: Nate Karstens Cc: stable@vger.kernel.org Fixes: 43a0c6751a32 ("strparser: Stream parser for messages") Reviewed-by: Jacob Keller Reviewed-by: Sabrina Dubroca Link: https://patch.msgid.link/20251106222835.1871628-1-nate.karstens@garmin.com Signed-off-by: Jakub Kicinski --- diff --git a/net/strparser/strparser.c b/net/strparser/strparser.c index 43b1f558b33db..e659fea2da70f 100644 --- a/net/strparser/strparser.c +++ b/net/strparser/strparser.c @@ -238,7 +238,7 @@ static int __strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb, strp_parser_err(strp, -EMSGSIZE, desc); break; } else if (len <= (ssize_t)head->len - - skb->len - stm->strp.offset) { + (ssize_t)skb->len - stm->strp.offset) { /* Length must be into new skb (and also * greater than zero) */