| From bippy-1.2.0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@kernel.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2021-47506: nfsd: fix use-after-free due to delegation race |
| |
| 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. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47506 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 3.17 with commit dff1399f8addf7129c49bb2227469da79cc30b47 and fixed in 4.4.296 with commit 04a8d07f3d58308b92630045560799a3faa3ebce |
| Issue introduced in 3.17 with commit dff1399f8addf7129c49bb2227469da79cc30b47 and fixed in 4.9.294 with commit 348714018139c39533c55661a0c7c990671396b4 |
| Issue introduced in 3.17 with commit dff1399f8addf7129c49bb2227469da79cc30b47 and fixed in 4.14.259 with commit 33645d3e22720cac1e4548f8fef57bf0649536ee |
| Issue introduced in 3.17 with commit dff1399f8addf7129c49bb2227469da79cc30b47 and fixed in 4.19.222 with commit 2becaa990b93cbd2928292c0b669d3abb6cf06d4 |
| Issue introduced in 3.17 with commit dff1399f8addf7129c49bb2227469da79cc30b47 and fixed in 5.4.168 with commit e0759696de6851d7536efddfdd2dfed4c4df1f09 |
| Issue introduced in 3.17 with commit dff1399f8addf7129c49bb2227469da79cc30b47 and fixed in 5.10.85 with commit eeb0711801f5e19ef654371b627682aed3b11373 |
| Issue introduced in 3.17 with commit dff1399f8addf7129c49bb2227469da79cc30b47 and fixed in 5.15.8 with commit 148c816f10fd11df27ca6a9b3238cdd42fa72cd3 |
| Issue introduced in 3.17 with commit dff1399f8addf7129c49bb2227469da79cc30b47 and fixed in 5.16 with commit 548ec0805c399c65ed66c6641be467f717833ab5 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2021-47506 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| fs/nfsd/nfs4state.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| 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 |
