GHSA-24C8-3JP4-H926
Vulnerability from github – Published: 2024-11-05 18:32 – Updated: 2024-11-08 21:33In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Unregister redistributor for failed vCPU creation
Alex reports that syzkaller has managed to trigger a use-after-free when tearing down a VM:
BUG: KASAN: slab-use-after-free in kvm_put_kvm+0x300/0xe68 virt/kvm/kvm_main.c:5769 Read of size 8 at addr ffffff801c6890d0 by task syz.3.2219/10758
CPU: 3 UID: 0 PID: 10758 Comm: syz.3.2219 Not tainted 6.11.0-rc6-dirty #64 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x17c/0x1a8 arch/arm64/kernel/stacktrace.c:317 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:324 __dump_stack lib/dump_stack.c:93 [inline] dump_stack_lvl+0x94/0xc0 lib/dump_stack.c:119 print_report+0x144/0x7a4 mm/kasan/report.c:377 kasan_report+0xcc/0x128 mm/kasan/report.c:601 __asan_report_load8_noabort+0x20/0x2c mm/kasan/report_generic.c:381 kvm_put_kvm+0x300/0xe68 virt/kvm/kvm_main.c:5769 kvm_vm_release+0x4c/0x60 virt/kvm/kvm_main.c:1409 __fput+0x198/0x71c fs/file_table.c:422 ____fput+0x20/0x30 fs/file_table.c:450 task_work_run+0x1cc/0x23c kernel/task_work.c:228 do_notify_resume+0x144/0x1a0 include/linux/resume_user_mode.h:50 el0_svc+0x64/0x68 arch/arm64/kernel/entry-common.c:169 el0t_64_sync_handler+0x90/0xfc arch/arm64/kernel/entry-common.c:730 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
Upon closer inspection, it appears that we do not properly tear down the MMIO registration for a vCPU that fails creation late in the game, e.g. a vCPU w/ the same ID already exists in the VM.
It is important to consider the context of commit that introduced this bug by moving the unregistration out of __kvm_vgic_vcpu_destroy(). That change correctly sought to avoid an srcu v. config_lock inversion by breaking up the vCPU teardown into two parts, one guarded by the config_lock.
Fix the use-after-free while avoiding lock inversion by adding a special-cased unregistration to __kvm_vgic_vcpu_destroy(). This is safe because failed vCPUs are torn down outside of the config_lock.
{
"affected": [],
"aliases": [
"CVE-2024-50114"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-11-05T18:15:14Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Unregister redistributor for failed vCPU creation\n\nAlex reports that syzkaller has managed to trigger a use-after-free when\ntearing down a VM:\n\n BUG: KASAN: slab-use-after-free in kvm_put_kvm+0x300/0xe68 virt/kvm/kvm_main.c:5769\n Read of size 8 at addr ffffff801c6890d0 by task syz.3.2219/10758\n\n CPU: 3 UID: 0 PID: 10758 Comm: syz.3.2219 Not tainted 6.11.0-rc6-dirty #64\n Hardware name: linux,dummy-virt (DT)\n Call trace:\n dump_backtrace+0x17c/0x1a8 arch/arm64/kernel/stacktrace.c:317\n show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:324\n __dump_stack lib/dump_stack.c:93 [inline]\n dump_stack_lvl+0x94/0xc0 lib/dump_stack.c:119\n print_report+0x144/0x7a4 mm/kasan/report.c:377\n kasan_report+0xcc/0x128 mm/kasan/report.c:601\n __asan_report_load8_noabort+0x20/0x2c mm/kasan/report_generic.c:381\n kvm_put_kvm+0x300/0xe68 virt/kvm/kvm_main.c:5769\n kvm_vm_release+0x4c/0x60 virt/kvm/kvm_main.c:1409\n __fput+0x198/0x71c fs/file_table.c:422\n ____fput+0x20/0x30 fs/file_table.c:450\n task_work_run+0x1cc/0x23c kernel/task_work.c:228\n do_notify_resume+0x144/0x1a0 include/linux/resume_user_mode.h:50\n el0_svc+0x64/0x68 arch/arm64/kernel/entry-common.c:169\n el0t_64_sync_handler+0x90/0xfc arch/arm64/kernel/entry-common.c:730\n el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598\n\nUpon closer inspection, it appears that we do not properly tear down the\nMMIO registration for a vCPU that fails creation late in the game, e.g.\na vCPU w/ the same ID already exists in the VM.\n\nIt is important to consider the context of commit that introduced this bug\nby moving the unregistration out of __kvm_vgic_vcpu_destroy(). That\nchange correctly sought to avoid an srcu v. config_lock inversion by\nbreaking up the vCPU teardown into two parts, one guarded by the\nconfig_lock.\n\nFix the use-after-free while avoiding lock inversion by adding a\nspecial-cased unregistration to __kvm_vgic_vcpu_destroy(). This is safe\nbecause failed vCPUs are torn down outside of the config_lock.",
"id": "GHSA-24c8-3jp4-h926",
"modified": "2024-11-08T21:33:53Z",
"published": "2024-11-05T18:32:12Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-50114"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6bcc2890b883ba1d16b8942937750565f6e9db0d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ae8f8b37610269009326f4318df161206c59843e"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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