| 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-2023-52707: sched/psi: Fix use-after-free in ep_remove_wait_queue() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| sched/psi: Fix use-after-free in ep_remove_wait_queue() |
| |
| If a non-root cgroup gets removed when there is a thread that registered |
| trigger and is polling on a pressure file within the cgroup, the polling |
| waitqueue gets freed in the following path: |
| |
| do_rmdir |
| cgroup_rmdir |
| kernfs_drain_open_files |
| cgroup_file_release |
| cgroup_pressure_release |
| psi_trigger_destroy |
| |
| However, the polling thread still has a reference to the pressure file and |
| will access the freed waitqueue when the file is closed or upon exit: |
| |
| fput |
| ep_eventpoll_release |
| ep_free |
| ep_remove_wait_queue |
| remove_wait_queue |
| |
| This results in use-after-free as pasted below. |
| |
| The fundamental problem here is that cgroup_file_release() (and |
| consequently waitqueue's lifetime) is not tied to the file's real lifetime. |
| Using wake_up_pollfree() here might be less than ideal, but it is in line |
| with the comment at commit 42288cb44c4b ("wait: add wake_up_pollfree()") |
| since the waitqueue's lifetime is not tied to file's one and can be |
| considered as another special case. While this would be fixable by somehow |
| making cgroup_file_release() be tied to the fput(), it would require |
| sizable refactoring at cgroups or higher layer which might be more |
| justifiable if we identify more cases like this. |
| |
| BUG: KASAN: use-after-free in _raw_spin_lock_irqsave+0x60/0xc0 |
| Write of size 4 at addr ffff88810e625328 by task a.out/4404 |
| |
| CPU: 19 PID: 4404 Comm: a.out Not tainted 6.2.0-rc6 #38 |
| Hardware name: Amazon EC2 c5a.8xlarge/, BIOS 1.0 10/16/2017 |
| Call Trace: |
| <TASK> |
| dump_stack_lvl+0x73/0xa0 |
| print_report+0x16c/0x4e0 |
| kasan_report+0xc3/0xf0 |
| kasan_check_range+0x2d2/0x310 |
| _raw_spin_lock_irqsave+0x60/0xc0 |
| remove_wait_queue+0x1a/0xa0 |
| ep_free+0x12c/0x170 |
| ep_eventpoll_release+0x26/0x30 |
| __fput+0x202/0x400 |
| task_work_run+0x11d/0x170 |
| do_exit+0x495/0x1130 |
| do_group_exit+0x100/0x100 |
| get_signal+0xd67/0xde0 |
| arch_do_signal_or_restart+0x2a/0x2b0 |
| exit_to_user_mode_prepare+0x94/0x100 |
| syscall_exit_to_user_mode+0x20/0x40 |
| do_syscall_64+0x52/0x90 |
| entry_SYSCALL_64_after_hwframe+0x63/0xcd |
| </TASK> |
| |
| Allocated by task 4404: |
| |
| kasan_set_track+0x3d/0x60 |
| __kasan_kmalloc+0x85/0x90 |
| psi_trigger_create+0x113/0x3e0 |
| pressure_write+0x146/0x2e0 |
| cgroup_file_write+0x11c/0x250 |
| kernfs_fop_write_iter+0x186/0x220 |
| vfs_write+0x3d8/0x5c0 |
| ksys_write+0x90/0x110 |
| do_syscall_64+0x43/0x90 |
| entry_SYSCALL_64_after_hwframe+0x63/0xcd |
| |
| Freed by task 4407: |
| |
| kasan_set_track+0x3d/0x60 |
| kasan_save_free_info+0x27/0x40 |
| ____kasan_slab_free+0x11d/0x170 |
| slab_free_freelist_hook+0x87/0x150 |
| __kmem_cache_free+0xcb/0x180 |
| psi_trigger_destroy+0x2e8/0x310 |
| cgroup_file_release+0x4f/0xb0 |
| kernfs_drain_open_files+0x165/0x1f0 |
| kernfs_drain+0x162/0x1a0 |
| __kernfs_remove+0x1fb/0x310 |
| kernfs_remove_by_name_ns+0x95/0xe0 |
| cgroup_addrm_files+0x67f/0x700 |
| cgroup_destroy_locked+0x283/0x3c0 |
| cgroup_rmdir+0x29/0x100 |
| kernfs_iop_rmdir+0xd1/0x140 |
| vfs_rmdir+0xfe/0x240 |
| do_rmdir+0x13d/0x280 |
| __x64_sys_rmdir+0x2c/0x30 |
| do_syscall_64+0x43/0x90 |
| entry_SYSCALL_64_after_hwframe+0x63/0xcd |
| |
| The Linux kernel CVE team has assigned CVE-2023-52707 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.2 with commit 0e94682b73bfa6c44c98af7a26771c9c08c055d5 and fixed in 5.4.232 with commit 7caeb5457bd01ccba0df1d6f4872f20d28e50b38 |
| Issue introduced in 5.2 with commit 0e94682b73bfa6c44c98af7a26771c9c08c055d5 and fixed in 5.10.169 with commit ec9c7aa08819f976b2492fa63c41b5712d2924b5 |
| Issue introduced in 5.2 with commit 0e94682b73bfa6c44c98af7a26771c9c08c055d5 and fixed in 5.15.95 with commit cca2b3feb70170ef6f0fbc4b4d91eea235a2b73a |
| Issue introduced in 5.2 with commit 0e94682b73bfa6c44c98af7a26771c9c08c055d5 and fixed in 6.1.13 with commit c6879a4dcefe92d870ab68cabaa9caeda4f2af5a |
| Issue introduced in 5.2 with commit 0e94682b73bfa6c44c98af7a26771c9c08c055d5 and fixed in 6.2 with commit c2dbe32d5db5c4ead121cf86dabd5ab691fb47fe |
| |
| 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-2023-52707 |
| 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: |
| kernel/sched/psi.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/7caeb5457bd01ccba0df1d6f4872f20d28e50b38 |
| https://git.kernel.org/stable/c/ec9c7aa08819f976b2492fa63c41b5712d2924b5 |
| https://git.kernel.org/stable/c/cca2b3feb70170ef6f0fbc4b4d91eea235a2b73a |
| https://git.kernel.org/stable/c/c6879a4dcefe92d870ab68cabaa9caeda4f2af5a |
| https://git.kernel.org/stable/c/c2dbe32d5db5c4ead121cf86dabd5ab691fb47fe |
