# CVE-2021-47262: linux: In the Linux kernel, the following vulnerability has been resolved:  KVM: x86: Ensure liveliness of nested VM-Enter f...

CVE-2021-47262 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47262, released May 21, 2024. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-47262
- Priority: High
- CVSS: 7.1 (high)
- EPSS: 0.0023
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 21, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  KVM: x86: Ensure liveliness of nested VM-Enter fail tracepoint message  Use the __string() machinery provided by the tracing subystem to make a copy of the string literals consumed by the "nested VM-Enter failed" tracepoint.  A complete copy is necessary to ensure that the tracepoint can't outlive the data/memory it consumes and deference stale memory.  Because the tracepoint itself is defined by kvm, if kvm-intel and/or kvm-amd are built as modules, the memory holding the string literals defined by the vendor modules will be freed when the module is unloaded, whereas the tracepoint and its data in the ring buffer will live until kvm is unloaded (or "indefinitely" if kvm is built-in).  This bug has existed since the tracepoint was added, but was recently exposed by a new check in tracing to detect exactly this type of bug.    fmt: '%s%s   ' current_buffer: ' vmx_dirty_log_t-140127  [003] ....  kvm_nested_vmenter_failed: '   WARNING: CPU: 3 PID: 140134 at kernel/trace/trace.c:3759 trace_check_vprintf+0x3be/0x3e0   CPU: 3 PID: 140134 Comm: less Not tainted 5.13.0-rc1-ce2e73ce600a-req #184   Hardware name: ASUS Q87M-E/Q87M-E, BIOS 1102 03/03/2014   RIP: 0010:trace_check_vprintf+0x3be/0x3e0   Code: <0f> 0b 44 8b 4c 24 1c e9 a9 fe ff ff c6 44 02 ff 00 49 8b 97 b0 20   RSP: 0018:ffffa895cc37bcb0 EFLAGS: 00010282   RAX: 0000000000000000 RBX: ffffa895cc37bd08 RCX: 0000000000000027   RDX: 0000000000000027 RSI: 00000000ffffdfff RDI: ffff9766cfad74f8   RBP: ffffffffc0a041d4 R08: ffff9766cfad74f0 R09: ffffa895cc37bad8   R10: 0000000000000001 R11: 0000000000000001 R12: ffffffffc0a041d4   R13: ffffffffc0f4dba8 R14: 0000000000000000 R15: ffff976409f2c000   FS:  00007f92fa200740(0000) GS:ffff9766cfac0000(0000) knlGS:0000000000000000   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033   CR2: 0000559bd11b0000 CR3: 000000019fbaa002 CR4: 00000000001726e0   Call Trace:    trace_event_printf+0x5e/0x80    trace_raw_output_kvm_nested_vmenter_failed+0x3a/0x60 [kvm]    print_trace_line+0x1dd/0x4e0    s_show+0x45/0x150    seq_read_iter+0x2d5/0x4c0    seq_read+0x106/0x150    vfs_read+0x98/0x180    ksys_read+0x5f/0xe0    do_syscall_64+0x40/0xb0    entry_SYSCALL_64_after_hwframe+0x44/0xae

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.10.46-1 | [DEBIAN-CVE-2021-47262](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47262.md) | May 21, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.10.46-1 | [DEBIAN-CVE-2021-47262](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47262.md) | May 21, 2024 |
| Linux | linux Debian 14 | 5.10.46-1 | [DEBIAN-CVE-2021-47262](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47262.md) | May 21, 2024 |

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