CVE-2021-47506 — nfsd: fix use-after-free due to delegation race

Affected: Linux

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.

LSN-0112-1 — Kernel Live Patch Security Notice

Affected: Ubuntu:Pro:16.04:LTS: linux-aws-hwe, Ubuntu:Pro:16.04:LTS: linux-aws, Ubuntu:Pro:16.04:LTS: linux-azure, Ubuntu:Pro:16.04:LTS: linux-gcp, Ubuntu:Pro:16.04:LTS: linux-hwe, Ubuntu:Pro:16.04:LTS: linux, Ubuntu:Pro:18.04:LTS: linux-aws, Ubuntu:Pro:18.04:LTS: linux-azure-4.15, Ubuntu:Pro:18.04:LTS: linux-gcp-4.15, Ubuntu:Pro:18.04:LTS: linux and 29 more

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.)(CVE-2021-47506)

Jann Horn discovered that the watch_queue event notification subsystem in the Linux kernel contained an out-of-bounds write vulnerability. A local attacker could use this to cause a denial of service (system crash) or escalate their privileges.)(CVE-2022-0995)

In the Linux kernel, the following vulnerability has been resolved: net: atlantic: eliminate double free in error handling logic Driver has a logic leak in ring data allocation/free, where aq_ring_free could be called multiple times on same ring, if system is under stress and got memory allocation error. Ring pointer was used as an indicator of fail…

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CVE-2021-47506 — nfsd: fix use-after-free due to delegation race

LSN-0112-1 — Kernel Live Patch Security Notice