CVE-2024-26603

Summary

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:

  • 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 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 ]

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxfcb3635f5018e53024c6be3c3213737f469f74ff < 8bd3eee7720c14b59a206bd05b98d7586bccf99aaffected
LinuxLinuxfcb3635f5018e53024c6be3c3213737f469f74ff < 627339cccdc9166792ecf96bc3c9f711a60ce996affected
LinuxLinuxfcb3635f5018e53024c6be3c3213737f469f74ff < b2479ab426cef7ab79a13005650eff956223ced2affected
LinuxLinuxfcb3635f5018e53024c6be3c3213737f469f74ff < 627e28cbb65564e55008315d9e02fbb90478bedaaffected
LinuxLinuxfcb3635f5018e53024c6be3c3213737f469f74ff < d877550eaf2dc9090d782864c96939397a3c6835affected
LinuxLinux5.14affected
LinuxLinux0 < 5.14unaffected
LinuxLinux5.15.150 <= 5.15.*unaffected
LinuxLinux6.1.79 <= 6.1.*unaffected
LinuxLinux6.6.18 <= 6.6.*unaffected
LinuxLinux6.7.6 <= 6.7.*unaffected
LinuxLinux6.8 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

CVE Program Container

Additional References

References