CVE-2025-39936
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk2th percentile - higher than 2% of all known CVEs
Summary
In the Linux kernel's CCP driver (crypto: ccp), a NULL pointer dereference vulnerability occurs when __sev_platform_shutdown_locked() is called with a NULL argument. This issue manifests on the shutdown path during suspend to disk, causing an Oops error and potential system crash.
Risk Assessment
An attacker with local access could exploit this vulnerability to cause a denial of service by triggering a suspend-to-disk operation, potentially disrupting critical services.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit 9770b428b1a2 or later). For production systems, apply the security patch from your distributor.
Original NVD description (English source)
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: <TASK> __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.