Description

In the Linux kernel, the following vulnerability has been resolved: KVM: s390: fix setting of fpc register kvm_arch_vcpu_ioctl_set_fpu() allows to set the floating point control (fpc) register of a guest cpu. The new value is tested for validity by temporarily loading it into the fpc register. This may lead to corruption of the fpc register of the host process: if an interrupt happens while the value is temporarily loaded into the fpc register, and within interrupt context floating point or vector registers are used, the current fp/vx registers are saved with save_fpu_regs() assuming they belong to user space and will be loaded into fp/vx registers when returning to user space. test_fp_ctl() restores the original user space / host process fpc register value, however it will be discarded, when returning to user space. In result the host process will incorrectly continue to run with the value that was supposed to be used for a guest cpu. Fix this by simply removing the test. There is another test right before the SIE context is entered which will handles invalid values. This results in a change of behaviour: invalid values will now be accepted instead of that the ioctl fails with -EINVAL. This seems to be acceptable, given that this interface is most likely not used anymore, and this is in addition the same behaviour implemented with the memory mapped interface (replace invalid values with zero) - see sync_regs() in kvm-s390.c.

Severity

 

CVSS Version 3.x CVSS Version 2.0

CVSS 3.x Severity and Metrics:

NIST: NVD

Base Score:  N/A

NVD assessment not yet provided.

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have not published a CVSS score for this CVE at this time. NVD Analysts use publicly available information at the time of analysis to associate CVSS vector strings.

CVSS 2.0 Severity and Metrics:

NIST: NVD

Base Score: N/A

NVD assessment not yet provided.

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have not published a CVSS score for this CVE at this time. NVD Analysts use publicly available information at the time of analysis to associate CVSS vector strings.

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

KVM: s390: fix setting of fpc register

kvm_arch_vcpu_ioctl_set_fpu() allows to set the floating point control
(fpc) register of a guest cpu. The new value is tested for validity by
temporarily loading it into the fpc register.

This may lead to corruption of the fpc register of the host process:
if an interrupt happens while the value is temporarily loaded into the fpc
register, and within interrupt context floating point or v

Linux https://git.kernel.org/stable/c/0671f42a9c1084db10d68ac347d08dbf6689ecb3 [No types assigned]

Linux https://git.kernel.org/stable/c/150a3a3871490e8c454ffbac2e60abeafcecff99 [No types assigned]

Linux https://git.kernel.org/stable/c/2823db0010c400e4b2b12d02aa5d0d3ecb15d7c7 [No types assigned]

Linux https://git.kernel.org/stable/c/3a04410b0bc7e056e0843ac598825dd359246d18 [No types assigned]

Linux https://git.kernel.org/stable/c/5e63c9ae8055109d805aacdaf2a4fe2c3b371ba1 [No types assigned]

Linux https://git.kernel.org/stable/c/732a3bea7aba5b15026ea42d14953c3425cc7dc2 [No types assigned]

Linux https://git.kernel.org/stable/c/b988b1bb0053c0dcd26187d29ef07566a565cf55 [No types assigned]

Linux https://git.kernel.org/stable/c/c87d7d910775a025e230fd6359b60627e392460f [No types assigned]