In the Linux kernel, the following vulnerability has been resolved:
x86/fpu: Stop relying on userspace for info to fault in xsave buffer
Before this change, the expected size of the user space buffer was taken from fx_sw->xstate_size. fx_sw->xstate_size can be changed from user-space, so it is possible construct a sigreturn frame where:
In this case, xrstor tries to restore and accesses the unmapped area which 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 and tries xrstor again. It will spin in this loop forever.
Instead, fault in the maximum size which can be touched by XRSTOR (taken from fpstate->user_size).
[ dhansen: tweak subject / changelog ]
The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.
Name | Vendor | Start Version | End Version |
---|---|---|---|
Linux_kernel | Linux | 5.14.0 (including) | 5.15.150 (excluding) |
Linux_kernel | Linux | 5.16.0 (including) | 6.1.79 (excluding) |
Linux_kernel | Linux | 6.2.0 (including) | 6.6.18 (excluding) |
Linux_kernel | Linux | 6.7.0 (including) | 6.7.6 (excluding) |