CVE-2024-41058: cachefiles: fix slab-use-after-free in fscache_withdraw_volume()
First published: Mon Jul 29 2024(Updated: )
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.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Linux kernel | >=5.17<6.1.101 | |
| Linux Linux kernel | >=6.2<6.6.42 | |
| Linux Linux kernel | >=6.7<6.9.11 | |
| redhat/kernel | <6.1.101 | 6.1.101 |
| redhat/kernel | <6.6.42 | 6.6.42 |
| redhat/kernel | <6.9.11 | 6.9.11 |
| redhat/kernel | <6.10 | 6.10 |
| debian/linux | 5.10.223-1 5.10.226-1 6.1.115-1 6.1.112-1 6.11.7-1 6.11.9-1 |
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Reference Links
- https://git.kernel.org/stable/c/38b88d544216f806d93a273a62ff8ebe82254003
- https://git.kernel.org/stable/c/522018a0de6b6fcce60c04f86dfc5f0e4b6a1b36
- https://git.kernel.org/stable/c/90f17e47f1e209c6a3c92a1d038a0a80c95c460e
- https://git.kernel.org/stable/c/9dd7f5663899ea13a6a73216106d9c13c37453e3
- https://launchpad.net/bugs/cve/CVE-2024-41058
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-41058
- https://nvd.nist.gov/vuln/detail/CVE-2024-41058
- https://security-tracker.debian.org/tracker/CVE-2024-41058
- https://ubuntu.com/security/CVE-2024-41058
- https://git.kernel.org/linus/522018a0de6b6fcce60c04f86dfc5f0e4b6a1b36
- https://lore.kernel.org/linux-cve-announce/2024072905-CVE-2024-41058-4593@gregkh/T
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=2301595
- https://access.redhat.com/errata/RHSA-2024:9315
- https://bugzilla.redhat.com/show_bug.cgi?id=2300432
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