| 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-2024-53218: f2fs: fix race in concurrent f2fs_stop_gc_thread |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| f2fs: fix race in concurrent f2fs_stop_gc_thread |
| |
| In my test case, concurrent calls to f2fs shutdown report the following |
| stack trace: |
| |
| Oops: general protection fault, probably for non-canonical address 0xc6cfff63bb5513fc: 0000 [#1] PREEMPT SMP PTI |
| CPU: 0 UID: 0 PID: 678 Comm: f2fs_rep_shutdo Not tainted 6.12.0-rc5-next-20241029-g6fb2fa9805c5-dirty #85 |
| Call Trace: |
| <TASK> |
| ? show_regs+0x8b/0xa0 |
| ? __die_body+0x26/0xa0 |
| ? die_addr+0x54/0x90 |
| ? exc_general_protection+0x24b/0x5c0 |
| ? asm_exc_general_protection+0x26/0x30 |
| ? kthread_stop+0x46/0x390 |
| f2fs_stop_gc_thread+0x6c/0x110 |
| f2fs_do_shutdown+0x309/0x3a0 |
| f2fs_ioc_shutdown+0x150/0x1c0 |
| __f2fs_ioctl+0xffd/0x2ac0 |
| f2fs_ioctl+0x76/0xe0 |
| vfs_ioctl+0x23/0x60 |
| __x64_sys_ioctl+0xce/0xf0 |
| x64_sys_call+0x2b1b/0x4540 |
| do_syscall_64+0xa7/0x240 |
| entry_SYSCALL_64_after_hwframe+0x76/0x7e |
| |
| The root cause is a race condition in f2fs_stop_gc_thread() called from |
| different f2fs shutdown paths: |
| |
| [CPU0] [CPU1] |
| ---------------------- ----------------------- |
| f2fs_stop_gc_thread f2fs_stop_gc_thread |
| gc_th = sbi->gc_thread |
| gc_th = sbi->gc_thread |
| kfree(gc_th) |
| sbi->gc_thread = NULL |
| < gc_th != NULL > |
| kthread_stop(gc_th->f2fs_gc_task) //UAF |
| |
| The commit c7f114d864ac ("f2fs: fix to avoid use-after-free in |
| f2fs_stop_gc_thread()") attempted to fix this issue by using a read |
| semaphore to prevent races between shutdown and remount threads, but |
| it fails to prevent all race conditions. |
| |
| Fix it by converting to write lock of s_umount in f2fs_do_shutdown(). |
| |
| The Linux kernel CVE team has assigned CVE-2024-53218 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.16 with commit 7950e9ac638e84518fbdd5c930939ad46a1068c5 and fixed in 6.6.64 with commit 794fa8792d4eacac191f1cbcc2e81b7369e4662a |
| Issue introduced in 4.16 with commit 7950e9ac638e84518fbdd5c930939ad46a1068c5 and fixed in 6.11.11 with commit 60457ed6c67625c87861f96912b4179dc2293896 |
| Issue introduced in 4.16 with commit 7950e9ac638e84518fbdd5c930939ad46a1068c5 and fixed in 6.12.2 with commit c631207897a9b3d41167ceca58e07f8f94720e42 |
| Issue introduced in 4.16 with commit 7950e9ac638e84518fbdd5c930939ad46a1068c5 and fixed in 6.13 with commit 7b0033dbc48340a1c1c3f12448ba17d6587ca092 |
| |
| 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-2024-53218 |
| 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/f2fs/file.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/794fa8792d4eacac191f1cbcc2e81b7369e4662a |
| https://git.kernel.org/stable/c/60457ed6c67625c87861f96912b4179dc2293896 |
| https://git.kernel.org/stable/c/c631207897a9b3d41167ceca58e07f8f94720e42 |
| https://git.kernel.org/stable/c/7b0033dbc48340a1c1c3f12448ba17d6587ca092 |
