CVE-2023-53669: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-53669 is a vulnerability in the Linux kernel related to TCP handling. The issue was discovered by David Ahern who reported crashes in skb_copy_ubufs() caused by TCP tx zerocopy using hugepages, and skb length bigger than ~68 KB (NVD, RedHat).

The vulnerability occurs when skb_copy_ubufs() assumed it could copy all payload using up to MAX_SKB_FRAGS order-0 pages. This assumption broke when BIG TCP was able to put up to 512 KB per skb. The issue specifically manifests when BIG TCP allows very large skbs (e.g., ~512 KB) and TCP TX zerocopy with hugepages is used (RedHat). The vulnerability has been assigned a CVSS v3.1 score of 7.0 with vector CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H (RedHat).

The vulnerability leads to Kernel Panic under specific, non-default conditions when BIG TCP/gso_max_size is configured large, zerocopy transmit is enabled, and traffic producing >64 KB skbs. While the primary impact is denial of service (DOS), there is a theoretical possibility for privilege escalation (RedHat).

The solution involves using higher order pages if needed, with the addition of __GFP_COMP to prevent memory leaks (NVD). The vulnerability has been patched in the Linux kernel with the commit 'tcp: fix skb_copy_ubufs() vs BIG TCP'.