1.4 KiB
CVE-2024-26603
Description
In the Linux kernel, the following vulnerability has been resolved:x86/fpu: Stop relying on userspace for info to fault in xsave bufferBefore this change, the expected size of the user space buffer wastaken from fx_sw->xstate_size. fx_sw->xstate_size can be changedfrom user-space, so it is possible construct a sigreturn frame where: * fx_sw->xstate_size is smaller than the size required by valid bits in fx_sw->xfeatures. * user-space unmaps parts of the sigrame fpu buffer so that not all of the buffer required by xrstor is accessible.In this case, xrstor tries to restore and accesses the unmapped areawhich results in a fault. But fault_in_readable succeeds because buf +fx_sw->xstate_size is within the still mapped area, so it goes back andtries xrstor again. It will spin in this loop forever.Instead, fault in the maximum size which can be touched by XRSTOR (takenfrom fpstate->user_size).[ dhansen: tweak subject / changelog ]
POC
Reference
No PoCs from references.