| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-50121: nfsd: cancel nfsd_shrinker_work using sync mode in nfs4_state_shutdown_net |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| nfsd: cancel nfsd_shrinker_work using sync mode in nfs4_state_shutdown_net |
| |
| In the normal case, when we excute `echo 0 > /proc/fs/nfsd/threads`, the |
| function `nfs4_state_destroy_net` in `nfs4_state_shutdown_net` will |
| release all resources related to the hashed `nfs4_client`. If the |
| `nfsd_client_shrinker` is running concurrently, the `expire_client` |
| function will first unhash this client and then destroy it. This can |
| lead to the following warning. Additionally, numerous use-after-free |
| errors may occur as well. |
| |
| nfsd_client_shrinker echo 0 > /proc/fs/nfsd/threads |
| |
| expire_client nfsd_shutdown_net |
| unhash_client ... |
| nfs4_state_shutdown_net |
| /* won't wait shrinker exit */ |
| /* cancel_work(&nn->nfsd_shrinker_work) |
| * nfsd_file for this /* won't destroy unhashed client1 */ |
| * client1 still alive nfs4_state_destroy_net |
| */ |
| |
| nfsd_file_cache_shutdown |
| /* trigger warning */ |
| kmem_cache_destroy(nfsd_file_slab) |
| kmem_cache_destroy(nfsd_file_mark_slab) |
| /* release nfsd_file and mark */ |
| __destroy_client |
| |
| ==================================================================== |
| BUG nfsd_file (Not tainted): Objects remaining in nfsd_file on |
| __kmem_cache_shutdown() |
| -------------------------------------------------------------------- |
| CPU: 4 UID: 0 PID: 764 Comm: sh Not tainted 6.12.0-rc3+ #1 |
| |
| dump_stack_lvl+0x53/0x70 |
| slab_err+0xb0/0xf0 |
| __kmem_cache_shutdown+0x15c/0x310 |
| kmem_cache_destroy+0x66/0x160 |
| nfsd_file_cache_shutdown+0xac/0x210 [nfsd] |
| nfsd_destroy_serv+0x251/0x2a0 [nfsd] |
| nfsd_svc+0x125/0x1e0 [nfsd] |
| write_threads+0x16a/0x2a0 [nfsd] |
| nfsctl_transaction_write+0x74/0xa0 [nfsd] |
| vfs_write+0x1a5/0x6d0 |
| ksys_write+0xc1/0x160 |
| do_syscall_64+0x5f/0x170 |
| entry_SYSCALL_64_after_hwframe+0x76/0x7e |
| |
| ==================================================================== |
| BUG nfsd_file_mark (Tainted: G B W ): Objects remaining |
| nfsd_file_mark on __kmem_cache_shutdown() |
| -------------------------------------------------------------------- |
| |
| dump_stack_lvl+0x53/0x70 |
| slab_err+0xb0/0xf0 |
| __kmem_cache_shutdown+0x15c/0x310 |
| kmem_cache_destroy+0x66/0x160 |
| nfsd_file_cache_shutdown+0xc8/0x210 [nfsd] |
| nfsd_destroy_serv+0x251/0x2a0 [nfsd] |
| nfsd_svc+0x125/0x1e0 [nfsd] |
| write_threads+0x16a/0x2a0 [nfsd] |
| nfsctl_transaction_write+0x74/0xa0 [nfsd] |
| vfs_write+0x1a5/0x6d0 |
| ksys_write+0xc1/0x160 |
| do_syscall_64+0x5f/0x170 |
| entry_SYSCALL_64_after_hwframe+0x76/0x7e |
| |
| To resolve this issue, cancel `nfsd_shrinker_work` using synchronous |
| mode in nfs4_state_shutdown_net. |
| |
| The Linux kernel CVE team has assigned CVE-2024-50121 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.10.220 with commit 2bbf10861d51dae76c6da7113516d0071c782653 and fixed in 5.10.233 with commit f67138dd338cb564ade7d3755c8cd4f68b46d397 |
| Issue introduced in 5.15.154 with commit 958294a3eb82026fcfff20b0287a90e9c854785e and fixed in 5.15.176 with commit 5ade4382de16c34d9259cb548f36ec5c4555913c |
| Issue introduced in 6.1.81 with commit f3ea5ec83d1a827f074b2b660749817e0bf2b23e and fixed in 6.1.123 with commit 36775f42e039b01d4abe8998bf66771a37d3cdcc |
| Issue introduced in 6.2 with commit 7c24fa225081f31bc6da6a355c1ba801889ab29a and fixed in 6.6.59 with commit f965dc0f099a54fca100acf6909abe52d0c85328 |
| Issue introduced in 6.2 with commit 7c24fa225081f31bc6da6a355c1ba801889ab29a and fixed in 6.11.6 with commit add1df5eba163a3a6ece11cb85890e2e410baaea |
| Issue introduced in 6.2 with commit 7c24fa225081f31bc6da6a355c1ba801889ab29a and fixed in 6.12 with commit d5ff2fb2e7167e9483846e34148e60c0c016a1f6 |
| |
| 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-2024-50121 |
| 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/f67138dd338cb564ade7d3755c8cd4f68b46d397 |
| https://git.kernel.org/stable/c/5ade4382de16c34d9259cb548f36ec5c4555913c |
| https://git.kernel.org/stable/c/36775f42e039b01d4abe8998bf66771a37d3cdcc |
| https://git.kernel.org/stable/c/f965dc0f099a54fca100acf6909abe52d0c85328 |
| https://git.kernel.org/stable/c/add1df5eba163a3a6ece11cb85890e2e410baaea |
| https://git.kernel.org/stable/c/d5ff2fb2e7167e9483846e34148e60c0c016a1f6 |
