Bug 1225049 (CVE-2023-52874)

Summary: VUL-0: CVE-2023-52874: kernel: x86/tdx: Zero out the missing RSI in TDX_HYPERCALL macro
Product: [Novell Products] SUSE Security Incidents Reporter: SMASH SMASH <smash_bz>
Component: IncidentsAssignee: Security Team bot <security-team>
Status: RESOLVED INVALID QA Contact: Security Team bot <security-team>
Severity: Minor    
Priority: P3 - Medium CC: carlos.lopez, jlee
Version: unspecified   
Target Milestone: ---   
Hardware: Other   
OS: Other   
URL: https://smash.suse.de/issue/407106/
Whiteboard: CVSSv3.1:SUSE:CVE-2023-52874:3.8:(AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N)
Found By: Security Response Team Services Priority:
Business Priority: Blocker: ---
Marketing QA Status: --- IT Deployment: ---

Description SMASH SMASH 2024-05-22 16:20:23 UTC
In the Linux kernel, the following vulnerability has been resolved:

x86/tdx: Zero out the missing RSI in TDX_HYPERCALL macro

In the TDX_HYPERCALL asm, after the TDCALL instruction returns from the
untrusted VMM, the registers that the TDX guest shares to the VMM need
to be cleared to avoid speculative execution of VMM-provided values.

RSI is specified in the bitmap of those registers, but it is missing
when zeroing out those registers in the current TDX_HYPERCALL.

It was there when it was originally added in commit 752d13305c78
("x86/tdx: Expand __tdx_hypercall() to handle more arguments"), but was
later removed in commit 1e70c680375a ("x86/tdx: Do not corrupt
frame-pointer in __tdx_hypercall()"), which was correct because %rsi is
later restored in the "pop %rsi".  However a later commit 7a3a401874be
("x86/tdx: Drop flags from __tdx_hypercall()") removed that "pop %rsi"
but forgot to add the "xor %rsi, %rsi" back.

Fix by adding it back.

References:
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2023-52874
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2023/CVE-2023-52874.mbox
https://git.kernel.org/stable/c/2191950d35d8f81620ea8d4e04d983f664fe3a8a
https://git.kernel.org/stable/c/de4c5bacca4f50233f1f791bec9eeb4dee1b14cd
https://git.kernel.org/stable/c/5d092b66119d774853cc9308522620299048a662
https://www.cve.org/CVERecord?id=CVE-2023-52874
Comment 2 Carlos López 2024-05-27 09:48:09 UTC
Nothing to do, closing.