UBUNTU-CVE-2022-48983
Vulnerability Summary
Timeline
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]
CVSS Metrics
- v3.1•MEDIUM•Score: 5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Affected Systems
- ubuntu•linux
< 5.15.0-67.74
- ubuntu•linux-allwinner-5.19
all
- ubuntu•linux-aws
< 5.15.0-1031.35
- ubuntu•linux-aws-5.0
all
- ubuntu•linux-aws-5.11
all
- ubuntu•linux-aws-5.13
all
- ubuntu•linux-aws-5.15
< 5.15.0-1031.35~20.04.1
- ubuntu•linux-aws-5.19
all
- ubuntu•linux-aws-5.3
all
- ubuntu•linux-aws-5.8
all
- ubuntu•linux-aws-6.2
all
- ubuntu•linux-aws-6.5
all
- ubuntu•linux-azure
all | < 5.15.0-1034.41
- ubuntu•linux-azure-5.11
all
- ubuntu•linux-azure-5.13
all
- ubuntu•linux-azure-5.15
< 5.15.0-1034.41~20.04.1
- ubuntu•linux-azure-5.19
all
- ubuntu•linux-azure-5.3
all
- ubuntu•linux-azure-5.8
all
- ubuntu•linux-azure-6.2
all
- ubuntu•linux-azure-6.5
all
- ubuntu•linux-azure-edge
all
- ubuntu•linux-azure-fde
all | < 5.15.0-1034.41.1
- ubuntu•linux-azure-fde-5.15
< 5.15.0-1034.41~20.04.1.2
- ubuntu•linux-azure-fde-5.19
all
- ubuntu•linux-azure-fde-6.2
all
- ubuntu•linux-bluefield
< 5.15.0-1014.16 | < 5.15.0-1014.16
- ubuntu•linux-gcp
all | < 5.15.0-1030.37
- ubuntu•linux-gcp-5.11
all
- ubuntu•linux-gcp-5.13
all
- ubuntu•linux-gcp-5.15
< 5.15.0-1030.37~20.04.1
- ubuntu•linux-gcp-5.19
all
- ubuntu•linux-gcp-5.3
all
- ubuntu•linux-gcp-5.8
all
- ubuntu•linux-gcp-6.2
all
- ubuntu•linux-gcp-6.5
all
- ubuntu•linux-gke
all | < 5.15.0-1028.33
- ubuntu•linux-gke-4.15
all
- ubuntu•linux-gke-5.15
all
- ubuntu•linux-gke-5.4
all
- ubuntu•linux-gkeop
< 5.15.0-1016.21
- ubuntu•linux-gkeop-5.15
< 5.15.0-1016.21~20.04.1
- ubuntu•linux-gkeop-5.4
all
- ubuntu•linux-hwe
all
- ubuntu•linux-hwe-5.11
all
- ubuntu•linux-hwe-5.13
all
- ubuntu•linux-hwe-5.15
< 5.15.0-67.74~20.04.1
- ubuntu•linux-hwe-5.19
all
- ubuntu•linux-hwe-5.8
all
- ubuntu•linux-hwe-6.2
all
Showing first 50 affected entries in server-rendered view.
References (6)
- https://ubuntu.com/security/CVE-2022-48983
- https://www.cve.org/CVERecord?id=CVE-2022-48983
- https://git.kernel.org/linus/998b30c3948e4d0b1097e639918c5cff332acac5
- https://git.kernel.org/stable/c/f895511de9d27fff71dad2c234ad53b4afd2b06c
- https://git.kernel.org/stable/c/d91edca1943453aaaba4f380f6f364346222e5cf
- https://git.kernel.org/stable/c/998b30c3948e4d0b1097e639918c5cff332acac5