| 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-2024-41058: cachefiles: fix slab-use-after-free in fscache_withdraw_volume() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| cachefiles: fix slab-use-after-free in fscache_withdraw_volume() |
| |
| We got the following issue in our fault injection stress test: |
| |
| ================================================================== |
| BUG: KASAN: slab-use-after-free in fscache_withdraw_volume+0x2e1/0x370 |
| Read of size 4 at addr ffff88810680be08 by task ondemand-04-dae/5798 |
| |
| CPU: 0 PID: 5798 Comm: ondemand-04-dae Not tainted 6.8.0-dirty #565 |
| Call Trace: |
| kasan_check_range+0xf6/0x1b0 |
| fscache_withdraw_volume+0x2e1/0x370 |
| cachefiles_withdraw_volume+0x31/0x50 |
| cachefiles_withdraw_cache+0x3ad/0x900 |
| cachefiles_put_unbind_pincount+0x1f6/0x250 |
| cachefiles_daemon_release+0x13b/0x290 |
| __fput+0x204/0xa00 |
| task_work_run+0x139/0x230 |
| |
| Allocated by task 5820: |
| __kmalloc+0x1df/0x4b0 |
| fscache_alloc_volume+0x70/0x600 |
| __fscache_acquire_volume+0x1c/0x610 |
| erofs_fscache_register_volume+0x96/0x1a0 |
| erofs_fscache_register_fs+0x49a/0x690 |
| erofs_fc_fill_super+0x6c0/0xcc0 |
| vfs_get_super+0xa9/0x140 |
| vfs_get_tree+0x8e/0x300 |
| do_new_mount+0x28c/0x580 |
| [...] |
| |
| Freed by task 5820: |
| kfree+0xf1/0x2c0 |
| fscache_put_volume.part.0+0x5cb/0x9e0 |
| erofs_fscache_unregister_fs+0x157/0x1b0 |
| erofs_kill_sb+0xd9/0x1c0 |
| deactivate_locked_super+0xa3/0x100 |
| vfs_get_super+0x105/0x140 |
| vfs_get_tree+0x8e/0x300 |
| do_new_mount+0x28c/0x580 |
| [...] |
| ================================================================== |
| |
| Following is the process that triggers the issue: |
| |
| mount failed | daemon exit |
| ------------------------------------------------------------ |
| deactivate_locked_super cachefiles_daemon_release |
| erofs_kill_sb |
| erofs_fscache_unregister_fs |
| fscache_relinquish_volume |
| __fscache_relinquish_volume |
| fscache_put_volume(fscache_volume, fscache_volume_put_relinquish) |
| zero = __refcount_dec_and_test(&fscache_volume->ref, &ref); |
| cachefiles_put_unbind_pincount |
| cachefiles_daemon_unbind |
| cachefiles_withdraw_cache |
| cachefiles_withdraw_volumes |
| list_del_init(&volume->cache_link) |
| fscache_free_volume(fscache_volume) |
| cache->ops->free_volume |
| cachefiles_free_volume |
| list_del_init(&cachefiles_volume->cache_link); |
| kfree(fscache_volume) |
| cachefiles_withdraw_volume |
| fscache_withdraw_volume |
| fscache_volume->n_accesses |
| // fscache_volume UAF !!! |
| |
| The fscache_volume in cache->volumes must not have been freed yet, but its |
| reference count may be 0. So use the new fscache_try_get_volume() helper |
| function try to get its reference count. |
| |
| If the reference count of fscache_volume is 0, fscache_put_volume() is |
| freeing it, so wait for it to be removed from cache->volumes. |
| |
| If its reference count is not 0, call cachefiles_withdraw_volume() with |
| reference count protection to avoid the above issue. |
| |
| The Linux kernel CVE team has assigned CVE-2024-41058 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.17 with commit fe2140e2f57fef8562e0f9b7cd447d2b08dc2f35 and fixed in 6.1.101 with commit 90f17e47f1e209c6a3c92a1d038a0a80c95c460e |
| Issue introduced in 5.17 with commit fe2140e2f57fef8562e0f9b7cd447d2b08dc2f35 and fixed in 6.6.42 with commit 9dd7f5663899ea13a6a73216106d9c13c37453e3 |
| Issue introduced in 5.17 with commit fe2140e2f57fef8562e0f9b7cd447d2b08dc2f35 and fixed in 6.9.11 with commit 38b88d544216f806d93a273a62ff8ebe82254003 |
| Issue introduced in 5.17 with commit fe2140e2f57fef8562e0f9b7cd447d2b08dc2f35 and fixed in 6.10 with commit 522018a0de6b6fcce60c04f86dfc5f0e4b6a1b36 |
| |
| 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-2024-41058 |
| 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/cachefiles/cache.c |
| include/trace/events/fscache.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/90f17e47f1e209c6a3c92a1d038a0a80c95c460e |
| https://git.kernel.org/stable/c/9dd7f5663899ea13a6a73216106d9c13c37453e3 |
| https://git.kernel.org/stable/c/38b88d544216f806d93a273a62ff8ebe82254003 |
| https://git.kernel.org/stable/c/522018a0de6b6fcce60c04f86dfc5f0e4b6a1b36 |
