CVE-2022-49562

Summary

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

KVM: x86: Use __try_cmpxchg_user() to update guest PTE A/D bits

Use the recently introduced __try_cmpxchg_user() to update guest PTE A/D bits instead of mapping the PTE into kernel address space. The VM_PFNMAP path is broken as it assumes that vm_pgoff is the base pfn of the mapped VMA range, which is conceptually wrong as vm_pgoff is the offset relative to the file and has nothing to do with the pfn. The horrific hack worked for the original use case (backing guest memory with /dev/mem), but leads to accessing "random" pfns for pretty much any other VM_PFNMAP case.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxbd53cb35a3e9adb73a834a36586e9ad80e877767 < 38b888911e8dc89b89d8147cfb1d2dbe6373bf78affected
LinuxLinuxbd53cb35a3e9adb73a834a36586e9ad80e877767 < 8089e5e1d18402fb8152d6b6815450a36fffa9b0affected
LinuxLinuxbd53cb35a3e9adb73a834a36586e9ad80e877767 < f122dfe4476890d60b8c679128cd2259ec96a24caffected
LinuxLinux5.2affected
LinuxLinux0 < 5.2unaffected
LinuxLinux5.17.13 <= 5.17.*unaffected
LinuxLinux5.18.2 <= 5.18.*unaffected
LinuxLinux5.19 <= *unaffected

Weaknesses

References