CVE-2021-47506 | BDVDB-2026-237392 Detail
LinuxLinux
Description#
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix use-after-free due to delegation race A delegation break could arrive as soon as we've called vfs_setlease. A delegation break runs a callback which immediately (in nfsd4_cb_recall_prepare) adds the delegation to del_recall_lru. If we then exit nfs4_set_delegation without hashing the delegation, it will be freed as soon as the callback is done with it, without ever being removed from del_recall_lru. Symptoms show up later as use-after-free or list corruption warnings, usually in the laundromat thread. I suspect aba2072f4523 "nfsd: grant read delegations to clients holding writes" made this bug easier to hit, but I looked as far back as v3.0 and it looks to me it already had the same problem. So I'm not sure where the bug was introduced; it may have been there from the beginning.
Impact#
Per CVSS v3.1: confidentiality impact high, integrity impact high, availability impact high. Attack vector: network.
Weaknesses#
No weakness recorded in the source data.
References#
- https://git.kernel.org/stable/c/04a8d07f3d58308b92630045560799a3faa3ebce
- https://git.kernel.org/stable/c/348714018139c39533c55661a0c7c990671396b4
- https://git.kernel.org/stable/c/33645d3e22720cac1e4548f8fef57bf0649536ee
- https://git.kernel.org/stable/c/2becaa990b93cbd2928292c0b669d3abb6cf06d4
- https://git.kernel.org/stable/c/e0759696de6851d7536efddfdd2dfed4c4df1f09
- https://git.kernel.org/stable/c/eeb0711801f5e19ef654371b627682aed3b11373
- https://git.kernel.org/stable/c/148c816f10fd11df27ca6a9b3238cdd42fa72cd3
- https://git.kernel.org/stable/c/548ec0805c399c65ed66c6641be467f717833ab5
Exploit#
No public exploit known
History#
- Version 1Record published in the CVE List.
- Version 2Most recent update recorded in the CVE List.