In the Linux kernel, the following vulnerability has been resolved:
crypto: ccp - Always pass in an error pointer to __sev_platform_shutdown_locked()
When
9770b428b1a2 ("crypto: ccp - Move dev_info/err messages for SEV/SNP init and shutdown")
moved the error messages dumping so that they don't need to be issued by
the callers, it missed the case where __sev_firmware_shutdown() calls
__sev_platform_shutdown_locked() with a NULL argument which leads to
a NULL ptr deref on the shutdown path, during suspend to disk:
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP NOPTI
CPU: 0 UID: 0 PID: 983 Comm: hib.sh Not tainted 6.17.0-rc4+ #1 PREEMPT(voluntary)
Hardware name: Supermicro Super Server/H12SSL-i, BIOS 2.5 09/08/2022
RIP: 0010:__sev_platform_shutdown_locked.cold+0x0/0x21 [ccp]
That rIP is:
00000000000006fd <__sev_platform_shutdown_locked.cold>:
6fd: 8b 13 mov (%rbx),%edx
6ff: 48 8b 7d 00 mov 0x0(%rbp),%rdi
703: 89 c1 mov %eax,%ecx
Code: 74 05 31 ff 41 89 3f 49 8b 3e 89 ea 48 c7 c6 a0 8e 54 a0 41 bf 92 ff ff ff e8 e5 2e 09 e1 c6 05 2a d4 38 00 01 e9 26 af ff ff <8b> 13 48 8b 7d 00 89 c1 48 c7 c6 18 90 54 a0 89 44 24 04 e8 c1 2e
RSP: 0018:ffffc90005467d00 EFLAGS: 00010282
RAX: 00000000ffffff92 RBX: 0000000000000000 RCX: 0000000000000000
^^^^^^^^^^^^^^^^
and %rbx is nice and clean.
Call Trace:
__sev_firmware_shutdown.isra.0
sev_dev_destroy
psp_dev_destroy
sp_destroy
pci_device_shutdown
device_shutdown
kernel_power_off
hibernate.cold
state_store
kernfs_fop_write_iter
vfs_write
ksys_write
do_syscall_64
entry_SYSCALL_64_after_hwframe
Pass in a pointer to the function-local error var in the caller.
With that addressed, suspending the ccp shows the error properly at
least:
ccp 0000:47:00.1: sev command 0x2 timed out, disabling PSP
ccp 0000:47:00.1: SEV: failed to SHUTDOWN error 0x0, rc -110
SEV-SNP: Leaking PFN range 0x146800-0x146a00
SEV-SNP: PFN 0x146800 unassigned, dumping non-zero entries in 2M PFN region: [0x146800 - 0x146a00]
...
ccp 0000:47:00.1: SEV-SNP firmware shutdown failed, rc -16, error 0x0
ACPI: PM: Preparing to enter system sleep state S5
kvm: exiting hardware virtualization
reboot: Power down
Btw, this driver is crying to be cleaned up to pass in a proper I/O
struct which can be used to store information between the different
functions, otherwise stuff like that will happen in the future again.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (5.5): severity, escalated by confirmed exploitation. This CVE's 5.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.1% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it