l2tp: pass correct message length to ip6_append_data (CVE-2024-26752)

Summary

l2tp: pass correct message length to ip6_append_data

Original description

The description as published by the source.

In the Linux kernel, the following vulnerability has been resolved:

l2tp: pass correct message length to ip6_append_data

l2tp_ip6_sendmsg needs to avoid accounting for the transport header
twice when splicing more data into an already partially-occupied skbuff.

To manage this, we check whether the skbuff contains data using
skb_queue_empty when deciding how much data to append using
ip6_append_data.

However, the code which performed the calculation was incorrect:

 ulen = len + skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0;

...due to C operator precedence, this ends up setting ulen to
transhdrlen for messages with a non-zero length, which results in
corrupted packets on the wire.

Add parentheses to correct the calculation in line with the original
intent.

Source: OSV.dev (Open Source Vulnerabilities) NVD OSV

Affected packages

Linux Kernel

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.19.308"}]},{"type":"ECOSYSTEM","events":[{"introduced":"4.20.0"},{"fixed":"5.4.270"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.5.0"},{"fixed":"5.10.211"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.150"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.80"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.19"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.6.0"},{"fixed":"6.7.7"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

Debian DEBIAN-CVE-2024-26752 linux Fixed in: 5.10.216-1
Ubuntu UBUNTU-CVE-2024-26752 linux-aws

Summary

Original description

Affected packages

Fix status by distribution

References