CVE-2024-57843 Information

Description

In the Linux kernel the following vulnerability has been resolved:

virtio-net: fix overflow inside virtnet_rq_alloc

When the frag just got a page then may lead to regression on VM. Specially if the sysctl net.core.high_order_alloc_disable value is 1 then the frag always get a page when do refill.

Which could see reliable crashes or scp failure (scp a file 100M in size to VM).

The issue is that the virtnet_rq_dma takes up 16 bytes at the beginning of a new frag. When the frag size is larger than PAGE_SIZE everything is fine. However if the frag is only one page and the total size of the buffer and virtnet_rq_dma is larger than one page an overflow may occur.

The commit f9dac92ba908 (irtio_ring: enable premapped mode whatever use_dma_api) introduced this problem. And we reverted some commits to fix this in last linux version. Now we try to enable it and fix this bug directly.

Here when the frag size is not enough we reduce the buffer len to fix this problem.

Reference

https://git.kernel.org/stable/c/67a11de8965c2ab19e215fb6651d44847e068614 https://git.kernel.org/stable/c/6aacd1484468361d1d04badfe75f264fa5314864 https://git.kernel.org/stable/c/a8f7d6963768b114ec9644ff0148dde4c104e84b