| 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-2024-53216: nfsd: release svc_expkey/svc_export with rcu_work |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| nfsd: release svc_expkey/svc_export with rcu_work |
| |
| The last reference for `cache_head` can be reduced to zero in `c_show` |
| and `e_show`(using `rcu_read_lock` and `rcu_read_unlock`). Consequently, |
| `svc_export_put` and `expkey_put` will be invoked, leading to two |
| issues: |
| |
| 1. The `svc_export_put` will directly free ex_uuid. However, |
| `e_show`/`c_show` will access `ex_uuid` after `cache_put`, which can |
| trigger a use-after-free issue, shown below. |
| |
| ================================================================== |
| BUG: KASAN: slab-use-after-free in svc_export_show+0x362/0x430 [nfsd] |
| Read of size 1 at addr ff11000010fdc120 by task cat/870 |
| |
| CPU: 1 UID: 0 PID: 870 Comm: cat Not tainted 6.12.0-rc3+ #1 |
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS |
| 1.16.1-2.fc37 04/01/2014 |
| Call Trace: |
| <TASK> |
| dump_stack_lvl+0x53/0x70 |
| print_address_description.constprop.0+0x2c/0x3a0 |
| print_report+0xb9/0x280 |
| kasan_report+0xae/0xe0 |
| svc_export_show+0x362/0x430 [nfsd] |
| c_show+0x161/0x390 [sunrpc] |
| seq_read_iter+0x589/0x770 |
| seq_read+0x1e5/0x270 |
| proc_reg_read+0xe1/0x140 |
| vfs_read+0x125/0x530 |
| ksys_read+0xc1/0x160 |
| do_syscall_64+0x5f/0x170 |
| entry_SYSCALL_64_after_hwframe+0x76/0x7e |
| |
| Allocated by task 830: |
| kasan_save_stack+0x20/0x40 |
| kasan_save_track+0x14/0x30 |
| __kasan_kmalloc+0x8f/0xa0 |
| __kmalloc_node_track_caller_noprof+0x1bc/0x400 |
| kmemdup_noprof+0x22/0x50 |
| svc_export_parse+0x8a9/0xb80 [nfsd] |
| cache_do_downcall+0x71/0xa0 [sunrpc] |
| cache_write_procfs+0x8e/0xd0 [sunrpc] |
| proc_reg_write+0xe1/0x140 |
| vfs_write+0x1a5/0x6d0 |
| ksys_write+0xc1/0x160 |
| do_syscall_64+0x5f/0x170 |
| entry_SYSCALL_64_after_hwframe+0x76/0x7e |
| |
| Freed by task 868: |
| kasan_save_stack+0x20/0x40 |
| kasan_save_track+0x14/0x30 |
| kasan_save_free_info+0x3b/0x60 |
| __kasan_slab_free+0x37/0x50 |
| kfree+0xf3/0x3e0 |
| svc_export_put+0x87/0xb0 [nfsd] |
| cache_purge+0x17f/0x1f0 [sunrpc] |
| nfsd_destroy_serv+0x226/0x2d0 [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 |
| |
| 2. We cannot sleep while using `rcu_read_lock`/`rcu_read_unlock`. |
| However, `svc_export_put`/`expkey_put` will call path_put, which |
| subsequently triggers a sleeping operation due to the following |
| `dput`. |
| |
| ============================= |
| WARNING: suspicious RCU usage |
| 5.10.0-dirty #141 Not tainted |
| ----------------------------- |
| ... |
| Call Trace: |
| dump_stack+0x9a/0xd0 |
| ___might_sleep+0x231/0x240 |
| dput+0x39/0x600 |
| path_put+0x1b/0x30 |
| svc_export_put+0x17/0x80 |
| e_show+0x1c9/0x200 |
| seq_read_iter+0x63f/0x7c0 |
| seq_read+0x226/0x2d0 |
| vfs_read+0x113/0x2c0 |
| ksys_read+0xc9/0x170 |
| do_syscall_64+0x33/0x40 |
| entry_SYSCALL_64_after_hwframe+0x67/0xd1 |
| |
| Fix these issues by using `rcu_work` to help release |
| `svc_expkey`/`svc_export`. This approach allows for an asynchronous |
| context to invoke `path_put` and also facilitates the freeing of |
| `uuid/exp/key` after an RCU grace period. |
| |
| The Linux kernel CVE team has assigned CVE-2024-53216 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.20 with commit 9ceddd9da13434a5906255c0fc528c385aded283 and fixed in 6.6.64 with commit bd8524148dd8c123334b066faa90590ba2ef8e6f |
| Issue introduced in 4.20 with commit 9ceddd9da13434a5906255c0fc528c385aded283 and fixed in 6.11.11 with commit 2e4854599200f4d021df8ae17e69221d7c149f3e |
| Issue introduced in 4.20 with commit 9ceddd9da13434a5906255c0fc528c385aded283 and fixed in 6.12.2 with commit ad4363a24a5746b257c0beb5d8cc68f9b62c173f |
| Issue introduced in 4.20 with commit 9ceddd9da13434a5906255c0fc528c385aded283 and fixed in 6.13 with commit f8c989a0c89a75d30f899a7cabdc14d72522bb8d |
| |
| 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-2024-53216 |
| 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/export.c |
| fs/nfsd/export.h |
| |
| |
| 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/bd8524148dd8c123334b066faa90590ba2ef8e6f |
| https://git.kernel.org/stable/c/2e4854599200f4d021df8ae17e69221d7c149f3e |
| https://git.kernel.org/stable/c/ad4363a24a5746b257c0beb5d8cc68f9b62c173f |
| https://git.kernel.org/stable/c/f8c989a0c89a75d30f899a7cabdc14d72522bb8d |
