CVE-2023-53083 Information

Description

In the Linux kernel the following vulnerability has been resolved:

nfsd: don’t replace page in rq_pages if it’s a continuation of last page

The splice read calls nfsd_splice_actor to put the pages containing file data into the svc_rqst->rq_pages array. It’s possible however to get a splice result that only has a partial page at the end if (e.g.) the filesystem hands back a short read that doesn’t cover the whole page.

nfsd_splice_actor will plop the partial page into its rq_pages array and return. Then later when nfsd_splice_actor is called again the remainder of the page may end up being filled out. At this point nfsd_splice_actor will put the page into the array again corrupting the reply. If this is done enough times rq_next_page will overrun the array and corrupt the trailing fields – the rq_respages and rq_next_page pointers themselves.

If we’ve already added the page to the array in the last pass don’t add it to the array a second time when dealing with a splice continuation. This was originally handled properly in nfsd_splice_actor but commit 91e23b1c3982 (\NFSD: Clean up nfsd_splice_actor()) removed the check for it.

Reference

https://git.kernel.org/stable/c/0101067f376eb7b9afd00279270f25d5111a091d https://git.kernel.org/stable/c/12eca509234acb6b666802edf77408bb70d7bfca https://git.kernel.org/stable/c/27c934dd8832dd40fd34776f916dc201e18b319b https://git.kernel.org/stable/c/51ddb84baff6f09ad62b5999ece3ec172e4e3568 https://git.kernel.org/stable/c/8235cd619db6e67f1d7d26c55f1f3e4e575c947d