| 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-2022-48983: io_uring: Fix a null-ptr-deref in io_tctx_exit_cb() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| io_uring: Fix a null-ptr-deref in io_tctx_exit_cb() |
| |
| Syzkaller reports a NULL deref bug as follows: |
| |
| BUG: KASAN: null-ptr-deref in io_tctx_exit_cb+0x53/0xd3 |
| Read of size 4 at addr 0000000000000138 by task file1/1955 |
| |
| CPU: 1 PID: 1955 Comm: file1 Not tainted 6.1.0-rc7-00103-gef4d3ea40565 #75 |
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014 |
| Call Trace: |
| <TASK> |
| dump_stack_lvl+0xcd/0x134 |
| ? io_tctx_exit_cb+0x53/0xd3 |
| kasan_report+0xbb/0x1f0 |
| ? io_tctx_exit_cb+0x53/0xd3 |
| kasan_check_range+0x140/0x190 |
| io_tctx_exit_cb+0x53/0xd3 |
| task_work_run+0x164/0x250 |
| ? task_work_cancel+0x30/0x30 |
| get_signal+0x1c3/0x2440 |
| ? lock_downgrade+0x6e0/0x6e0 |
| ? lock_downgrade+0x6e0/0x6e0 |
| ? exit_signals+0x8b0/0x8b0 |
| ? do_raw_read_unlock+0x3b/0x70 |
| ? do_raw_spin_unlock+0x50/0x230 |
| arch_do_signal_or_restart+0x82/0x2470 |
| ? kmem_cache_free+0x260/0x4b0 |
| ? putname+0xfe/0x140 |
| ? get_sigframe_size+0x10/0x10 |
| ? do_execveat_common.isra.0+0x226/0x710 |
| ? lockdep_hardirqs_on+0x79/0x100 |
| ? putname+0xfe/0x140 |
| ? do_execveat_common.isra.0+0x238/0x710 |
| exit_to_user_mode_prepare+0x15f/0x250 |
| syscall_exit_to_user_mode+0x19/0x50 |
| do_syscall_64+0x42/0xb0 |
| entry_SYSCALL_64_after_hwframe+0x63/0xcd |
| RIP: 0023:0x0 |
| Code: Unable to access opcode bytes at 0xffffffffffffffd6. |
| RSP: 002b:00000000fffb7790 EFLAGS: 00000200 ORIG_RAX: 000000000000000b |
| RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 |
| RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 |
| RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 |
| R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 |
| R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 |
| </TASK> |
| Kernel panic - not syncing: panic_on_warn set ... |
| |
| This happens because the adding of task_work from io_ring_exit_work() |
| isn't synchronized with canceling all work items from eg exec. The |
| execution of the two are ordered in that they are both run by the task |
| itself, but if io_tctx_exit_cb() is queued while we're canceling all |
| work items off exec AND gets executed when the task exits to userspace |
| rather than in the main loop in io_uring_cancel_generic(), then we can |
| find current->io_uring == NULL and hit the above crash. |
| |
| It's safe to add this NULL check here, because the execution of the two |
| paths are done by the task itself. |
| |
| [axboe: add code comment and also put an explanation in the commit msg] |
| |
| The Linux kernel CVE team has assigned CVE-2022-48983 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.12 with commit d56d938b4bef3e1421a42023cdcd6e13c1f50831 and fixed in 5.15.83 with commit f895511de9d27fff71dad2c234ad53b4afd2b06c |
| Issue introduced in 5.12 with commit d56d938b4bef3e1421a42023cdcd6e13c1f50831 and fixed in 6.0.13 with commit d91edca1943453aaaba4f380f6f364346222e5cf |
| Issue introduced in 5.12 with commit d56d938b4bef3e1421a42023cdcd6e13c1f50831 and fixed in 6.1 with commit 998b30c3948e4d0b1097e639918c5cff332acac5 |
| |
| 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-2022-48983 |
| 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: |
| io_uring/io_uring.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/f895511de9d27fff71dad2c234ad53b4afd2b06c |
| https://git.kernel.org/stable/c/d91edca1943453aaaba4f380f6f364346222e5cf |
| https://git.kernel.org/stable/c/998b30c3948e4d0b1097e639918c5cff332acac5 |
