Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
tcp: fix skb_copy_ubufs() vs BIG TCP
David Ahern reported crashes in skb_copy_ubufs() caused by TCP tx zerocopy using hugepages, and skb length bigger than ~68 KB.
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.
We did not hit this bug at Google because we use CONFIG_MAX_SKB_FRAGS=45 and limit gso_max_size to 180000.
A solution is to use higher order pages if needed.
v2: add missing __GFP_COMP, or we leak memory.
Details
- Affected product:
- AlmaLinux 9.2 ESU , TuxCare 9.6 ESU
- Affected packages:
- kernel @ 5.14.0 (+1 more)
In the Linux kernel, the following vulnerability has been resolved:
tcp: fix skb_copy_ubufs() vs BIG TCP
David Ahern reported crashes in skb_copy_ubufs() caused by TCP tx zerocopy using hugepages, and skb length bigger than ~68 KB.
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.
We did not hit this bug at Google because we use CONFIG_MAX_SKB_FRAGS=45 and limit gso_max_size to 180000.
A solution is to use higher order pages if needed.
v2: add missing __GFP_COMP, or we leak memory.