CVE-2024-26752

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> l2tp: pass correct message length to ip6_append_data<br /> <br /> l2tp_ip6_sendmsg needs to avoid accounting for the transport header<br /> twice when splicing more data into an already partially-occupied skbuff.<br /> <br /> To manage this, we check whether the skbuff contains data using<br /> skb_queue_empty when deciding how much data to append using<br /> ip6_append_data.<br /> <br /> However, the code which performed the calculation was incorrect:<br /> <br /> ulen = len + skb_queue_empty(&amp;sk-&gt;sk_write_queue) ? transhdrlen : 0;<br /> <br /> ...due to C operator precedence, this ends up setting ulen to<br /> transhdrlen for messages with a non-zero length, which results in<br /> corrupted packets on the wire.<br /> <br /> Add parentheses to correct the calculation in line with the original<br /> intent.