GHSA-277M-9MG9-WH9Q
Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-15 06:32In the Linux kernel, the following vulnerability has been resolved:
ocfs2: rebase copied fsdlm LVB pointers in locking_state
The locking_state debugfs iterator snapshots struct ocfs2_lock_res by value under ocfs2_dlm_tracking_lock and later formats that copy in ocfs2_dlm_seq_show(). That is fine for the inline fields, but the userspace fsdlm stack stores the LVB through lksb_fsdlm.sb_lvbptr. Once the iterator drops the tracking lock, a copied non-NULL sb_lvbptr still points into the original lockres owner, so teardown can free that container before the debugfs dump walks the raw LVB bytes.
Rebase the copied sb_lvbptr to the copied l_lksb before dumping the raw LVB. The seq snapshot already carries the inline LVB storage reserved in struct ocfs2_dlm_lksb, so the debugfs reader can dump the copied bytes without borrowing the original lockres lifetime.
The buggy scenario involves two paths, with each column showing the order within that path:
locking_state reader: lockres teardown: 1. ocfs2_dlm_seq_start()/next() 1. file release or another owner copies struct ocfs2_lock_res teardown reaches 2. ocfs2_dlm_seq_show() formats ocfs2_lock_res_free() the copied row 2. the lockres is removed from the 3. ocfs2_dlm_lvb() follows the tracking list copied sb_lvbptr 3. the owner frees the original lockres container
Validation reproduced this kernel report: KASAN slab-use-after-free in ocfs2_dlm_seq_show+0x1bd/0x430 RIP: 0033:0x7f8ec4b1e29d The buggy address belongs to the object at ffff88810a1e0800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 368 bytes inside of freed 1024-byte region [ffff88810a1e0800, ffff88810a1e0c00) Read of size 1 Call trace: dump_stack_lvl+0x66/0xa0 print_report+0xce/0x630 ocfs2_dlm_seq_show+0x1bd/0x430 (fs/ocfs2/dlmglue.c:3137) srso_alias_return_thunk+0x5/0xfbef5 __virt_addr_valid+0x19f/0x330 kasan_report+0xe0/0x110 seq_read_iter+0x29d/0x790 seq_read+0x20a/0x280 find_held_lock+0x2b/0x80 rcu_read_unlock+0x18/0x70 full_proxy_read+0x9e/0xd0 vfs_read+0x12c/0x590 ksys_read+0xd2/0x170 do_user_addr_fault+0x65a/0x890 do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated by task stack: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 ocfs2_file_open+0x13e/0x300 do_dentry_open+0x233/0x7f0 vfs_open+0x5a/0x1b0 path_openat+0x66d/0x1540 do_file_open+0x186/0x2b0 do_sys_openat2+0xce/0x150 __x64_sys_openat+0xd0/0x140 do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task stack: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x5f/0x80 kfree+0x313/0x590 ocfs2_file_release+0x138/0x260 __fput+0x1df/0x4b0 fput_close_sync+0xd2/0x170 __x64_sys_close+0x55/0x90 do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f
{
"affected": [],
"aliases": [
"CVE-2026-74351"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T06:22:36Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: rebase copied fsdlm LVB pointers in locking_state\n\nThe locking_state debugfs iterator snapshots struct ocfs2_lock_res by\nvalue under ocfs2_dlm_tracking_lock and later formats that copy in\nocfs2_dlm_seq_show(). That is fine for the inline fields, but the\nuserspace fsdlm stack stores the LVB through lksb_fsdlm.sb_lvbptr. Once\nthe iterator drops the tracking lock, a copied non-NULL sb_lvbptr still\npoints into the original lockres owner, so teardown can free that\ncontainer before the debugfs dump walks the raw LVB bytes.\n\nRebase the copied sb_lvbptr to the copied l_lksb before dumping the raw\nLVB. The seq snapshot already carries the inline LVB storage reserved in\nstruct ocfs2_dlm_lksb, so the debugfs reader can dump the copied bytes\nwithout borrowing the original lockres lifetime.\n\nThe buggy scenario involves two paths, with each column showing the order\nwithin that path:\n\nlocking_state reader: lockres teardown:\n1. ocfs2_dlm_seq_start()/next() 1. file release or another owner\n copies struct ocfs2_lock_res teardown reaches\n2. ocfs2_dlm_seq_show() formats ocfs2_lock_res_free()\n the copied row 2. the lockres is removed from the\n3. ocfs2_dlm_lvb() follows the tracking list\n copied sb_lvbptr 3. the owner frees the original\n lockres container\n\nValidation reproduced this kernel report:\nKASAN slab-use-after-free in ocfs2_dlm_seq_show+0x1bd/0x430\nRIP: 0033:0x7f8ec4b1e29d\nThe buggy address belongs to the object at ffff88810a1e0800 which belongs\nto the cache kmalloc-1k of size 1024\nThe buggy address is located 368 bytes inside of freed 1024-byte region\n[ffff88810a1e0800, ffff88810a1e0c00)\nRead of size 1\nCall trace:\n dump_stack_lvl+0x66/0xa0\n print_report+0xce/0x630\n ocfs2_dlm_seq_show+0x1bd/0x430 (fs/ocfs2/dlmglue.c:3137)\n srso_alias_return_thunk+0x5/0xfbef5\n __virt_addr_valid+0x19f/0x330\n kasan_report+0xe0/0x110\n seq_read_iter+0x29d/0x790\n seq_read+0x20a/0x280\n find_held_lock+0x2b/0x80\n rcu_read_unlock+0x18/0x70\n full_proxy_read+0x9e/0xd0\n vfs_read+0x12c/0x590\n ksys_read+0xd2/0x170\n do_user_addr_fault+0x65a/0x890\n do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\nAllocated by task stack:\n kasan_save_stack+0x33/0x60\n kasan_save_track+0x14/0x30\n __kasan_kmalloc+0xaa/0xb0\n ocfs2_file_open+0x13e/0x300\n do_dentry_open+0x233/0x7f0\n vfs_open+0x5a/0x1b0\n path_openat+0x66d/0x1540\n do_file_open+0x186/0x2b0\n do_sys_openat2+0xce/0x150\n __x64_sys_openat+0xd0/0x140\n do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\nFreed by task stack:\n kasan_save_stack+0x33/0x60\n kasan_save_track+0x14/0x30\n kasan_save_free_info+0x3b/0x60\n __kasan_slab_free+0x5f/0x80\n kfree+0x313/0x590\n ocfs2_file_release+0x138/0x260\n __fput+0x1df/0x4b0\n fput_close_sync+0xd2/0x170\n __x64_sys_close+0x55/0x90\n do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)\n entry_SYSCALL_64_after_hwframe+0x77/0x7f",
"id": "GHSA-277m-9mg9-wh9q",
"modified": "2026-08-15T06:32:31Z",
"published": "2026-08-15T06:32:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74351"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/07aa4a8ebacde3d0ba50f60d2964f274ee7629bc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/185427b5f7a209254c85c18aad5a4a8e009b2f30"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/610a0d2a35496738e1472fb0f318d5008a1c634f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6b38a5b8ee951e5b244e9a3c3d28d0f5e7c51411"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8614a8f7e81edd34c9f67e454e7024fd12a2a341"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/93612d48fa42b3d1a637eb9279e15281c611c000"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bb44a7690a4d553da705919cf666a80f5ca9011c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e037c1250cc90e7aacb002357d1b0399fc65ecfc"
}
],
"schema_version": "1.4.0",
"severity": []
}
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