CVE-2021-47262

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> KVM: x86: Ensure liveliness of nested VM-Enter fail tracepoint message<br /> <br /> Use the __string() machinery provided by the tracing subystem to make a<br /> copy of the string literals consumed by the "nested VM-Enter failed"<br /> tracepoint. A complete copy is necessary to ensure that the tracepoint<br /> can&amp;#39;t outlive the data/memory it consumes and deference stale memory.<br /> <br /> Because the tracepoint itself is defined by kvm, if kvm-intel and/or<br /> kvm-amd are built as modules, the memory holding the string literals<br /> defined by the vendor modules will be freed when the module is unloaded,<br /> whereas the tracepoint and its data in the ring buffer will live until<br /> kvm is unloaded (or "indefinitely" if kvm is built-in).<br /> <br /> This bug has existed since the tracepoint was added, but was recently<br /> exposed by a new check in tracing to detect exactly this type of bug.<br /> <br /> fmt: &amp;#39;%s%s<br /> &amp;#39; current_buffer: &amp;#39; vmx_dirty_log_t-140127 [003] .... kvm_nested_vmenter_failed: &amp;#39;<br /> WARNING: CPU: 3 PID: 140134 at kernel/trace/trace.c:3759 trace_check_vprintf+0x3be/0x3e0<br /> CPU: 3 PID: 140134 Comm: less Not tainted 5.13.0-rc1-ce2e73ce600a-req #184<br /> Hardware name: ASUS Q87M-E/Q87M-E, BIOS 1102 03/03/2014<br /> RIP: 0010:trace_check_vprintf+0x3be/0x3e0<br /> Code: 0b 44 8b 4c 24 1c e9 a9 fe ff ff c6 44 02 ff 00 49 8b 97 b0 20<br /> RSP: 0018:ffffa895cc37bcb0 EFLAGS: 00010282<br /> RAX: 0000000000000000 RBX: ffffa895cc37bd08 RCX: 0000000000000027<br /> RDX: 0000000000000027 RSI: 00000000ffffdfff RDI: ffff9766cfad74f8<br /> RBP: ffffffffc0a041d4 R08: ffff9766cfad74f0 R09: ffffa895cc37bad8<br /> R10: 0000000000000001 R11: 0000000000000001 R12: ffffffffc0a041d4<br /> R13: ffffffffc0f4dba8 R14: 0000000000000000 R15: ffff976409f2c000<br /> FS: 00007f92fa200740(0000) GS:ffff9766cfac0000(0000) knlGS:0000000000000000<br /> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br /> CR2: 0000559bd11b0000 CR3: 000000019fbaa002 CR4: 00000000001726e0<br /> Call Trace:<br /> trace_event_printf+0x5e/0x80<br /> trace_raw_output_kvm_nested_vmenter_failed+0x3a/0x60 [kvm]<br /> print_trace_line+0x1dd/0x4e0<br /> s_show+0x45/0x150<br /> seq_read_iter+0x2d5/0x4c0<br /> seq_read+0x106/0x150<br /> vfs_read+0x98/0x180<br /> ksys_read+0x5f/0xe0<br /> do_syscall_64+0x40/0xb0<br /> entry_SYSCALL_64_after_hwframe+0x44/0xae