other: 0.855
graphic: 0.843
permissions: 0.714
device: 0.705
performance: 0.667
socket: 0.667
network: 0.662
PID: 0.660
debug: 0.617
files: 0.563
vnc: 0.516
semantic: 0.508
boot: 0.465
KVM: 0.401

Possible regression in QEMU 5.0.0 after CVE-2020-10702 (segmentation fault)

I've come across a very specific situation, but I'm sure it could be replicated in other cases.

In QEMU 5.0.0 when I use user emulation with a cURL binary for aarch64 and connect to a server using TLS 1.2 and ECDHE-ECDSA-CHACHA20-POLY1305 cypher a segmentation fault occurs.

I attach a Dockerfile that reproduces this crash and the strace output with and without the de0b1bae6461f67243282555475f88b2384a1eb9 commit reverted.



This is a compiler bug affecting (at least) libcrypto.so.1.1:

  179d90:       d503233f        paciasp
  179d94:       a9bb7bfd        stp     x29, x30, [sp, #-80]!
...
  17a400:       d50323bf        autiasp
  17a404:       f84507fd        ldr     x29, [sp], #80
  17a408:       d65f03c0        ret

The PAC happens with the initial sp:

  X30=0000005501de55fc  SP=00000055018477a0

while the AUTH happens with the decremented sp:

  X30=0011005501de55fc  SP=0000005501847750

Since the salt (sp) is different for the two operations, the
authorization should and does fail:

  X30=0020005501de55fc

Note bit 53 is now set in x30, which is the error indication.

The compiler must move the authiasp down below the ldr pop.