CVE-2022-48764

In the Linux kernel, the following vulnerability has been resolved:

KVM: x86: Free kvm_cpuid_entry2 array on post-KVM_RUN KVM_SET_CPUID{,2}

Free the struct kvm_cpuid_entry2 array on successful post-KVM_RUN KVM_SET_CPUID{,2} to fix a memory leak, the callers of kvm_set_cpuid() free the array only on failure.

BUG: memory leak unreferenced object 0xffff88810963a800 (size 2048): comm syz-executor025, pid 3610, jiffies 4294944928 (age 8.080s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 0d 00 00 00 ……………. 47 65 6e 75 6e 74 65 6c 69 6e 65 49 00 00 00 00 GenuntelineI…. backtrace: [] kmalloc_node include/linux/slab.h:604 [inline] [] kvmalloc_node+0x3e/0x100 mm/util.c:580 [] kvmalloc include/linux/slab.h:732 [inline] [] vmemdup_user+0x22/0x100 mm/util.c:199 [] kvm_vcpu_ioctl_set_cpuid2+0x8f/0xf0 arch/x86/kvm/cpuid.c:423 [] kvm_arch_vcpu_ioctl+0xb99/0x1e60 arch/x86/kvm/x86.c:5251 [] kvm_vcpu_ioctl+0x4ad/0x950 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4066 [] vfs_ioctl fs/ioctl.c:51 [inline] [] __do_sys_ioctl fs/ioctl.c:874 [inline] [] __se_sys_ioctl fs/ioctl.c:860 [inline] [] __x64_sys_ioctl+0xfc/0x140 fs/ioctl.c:860 [] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 [] entry_SYSCALL_64_after_hwframe+0x44/0xae

Weakness

The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://git.kernel.org/stable/c/811f95ff95270e6048197821434d9301e3d7f07c
• https://git.kernel.org/stable/c/b9ee734a14bb685b2088f2176d82b34cb4e30dbc
• https://git.kernel.org/stable/c/811f95ff95270e6048197821434d9301e3d7f07c
• https://git.kernel.org/stable/c/b9ee734a14bb685b2088f2176d82b34cb4e30dbc