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.
OS | Version | Architecture | Package | Version | Filename |
---|---|---|---|---|---|
ubuntu | 18.04 | noarch | linux | < any | UNKNOWN |
ubuntu | 20.04 | noarch | linux | < any | UNKNOWN |
ubuntu | 18.04 | noarch | linux-aws | < any | UNKNOWN |
ubuntu | 20.04 | noarch | linux-aws | < any | UNKNOWN |
ubuntu | 18.04 | noarch | linux-aws-5.4 | < any | UNKNOWN |
ubuntu | 16.04 | noarch | linux-aws-hwe | < any | UNKNOWN |
ubuntu | 20.04 | noarch | linux-azure | < any | UNKNOWN |
ubuntu | 14.04 | noarch | linux-azure | < any | UNKNOWN |
ubuntu | 16.04 | noarch | linux-azure | < any | UNKNOWN |
ubuntu | 18.04 | noarch | linux-azure-4.15 | < any | UNKNOWN |
git.kernel.org/linus/548ec0805c399c65ed66c6641be467f717833ab5 (5.16-rc5)
git.kernel.org/stable/c/04a8d07f3d58308b92630045560799a3faa3ebce
git.kernel.org/stable/c/148c816f10fd11df27ca6a9b3238cdd42fa72cd3
git.kernel.org/stable/c/2becaa990b93cbd2928292c0b669d3abb6cf06d4
git.kernel.org/stable/c/33645d3e22720cac1e4548f8fef57bf0649536ee
git.kernel.org/stable/c/348714018139c39533c55661a0c7c990671396b4
git.kernel.org/stable/c/548ec0805c399c65ed66c6641be467f717833ab5
git.kernel.org/stable/c/e0759696de6851d7536efddfdd2dfed4c4df1f09
git.kernel.org/stable/c/eeb0711801f5e19ef654371b627682aed3b11373
launchpad.net/bugs/cve/CVE-2021-47506
nvd.nist.gov/vuln/detail/CVE-2021-47506
security-tracker.debian.org/tracker/CVE-2021-47506
www.cve.org/CVERecord?id=CVE-2021-47506