GHSA-7R62-VJJF-3924
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/dlm: require a ref for locking_state debugfs open
debug_lockres_open() copies inode->i_private into struct debug_lockres and debug_lockres_release() later drops that pointer with dlm_put(). That only works if open successfully pins the struct dlm_ctxt.
Today open calls dlm_grab(dlm) but ignores its return value. Once the last domain unregister has removed the context from dlm_domains, dlm_grab() returns NULL, yet open still stores the raw pointer and returns success. The later release path is outside the debugfs removal barrier, so it can call dlm_put() after dlm_free_ctxt_mem() has freed the context. KASAN reports this as a slab-use-after-free in dlm_put() called from debug_lockres_release().
Fail the open when dlm_grab() cannot acquire the reference and unwind the seq_file private state before returning. That keeps locking_state from handing out a file descriptor whose release path does not own the dlm_ctxt.
The buggy scenario involves two paths, with each column showing the order within that path:
locking_state debugfs open: last domain unregister: 1. debug_lockres_open() reads 1. dlm_unregister_domain() calls inode->i_private. dlm_complete_dlm_shutdown(). 2. debug_lockres_open() calls 2. shutdown removes the dlm_ctxt from dlm_grab(dlm) and gets NULL. dlm_domains. 3. open still stores the raw dlm 3. final teardown reaches pointer in dl->dl_ctxt and dlm_free_ctxt_mem() and frees it. returns success. 4. debug_lockres_release() later calls dlm_put(dl->dl_ctxt).
Validation reproduced this kernel report: KASAN slab-use-after-free in dlm_put+0x82/0x200 RIP: 0033:0x7f4d349bc9e0 The buggy address belongs to the object at ffff888103a3c000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 816 bytes inside of freed 2048-byte region [ffff888103a3c000, ffff888103a3c800) Write of size 4 Call trace: dump_stack_lvl+0x66/0xa0 (?:?) print_report+0xd0/0x630 (?:?) dlm_put+0x82/0x200 (?:?) srso_alias_return_thunk+0x5/0xfbef5 (?:?) __virt_addr_valid+0x188/0x2f0 (?:?) kasan_report+0xe4/0x120 (?:?) kasan_check_range+0x105/0x1b0 (?:?) debug_lockres_release+0x53/0x80 (fs/ocfs2/dlm/dlmdebug.c:587) dlm_put+0x9/0x200 (?:?) debug_lockres_release+0x5c/0x80 (fs/ocfs2/dlm/dlmdebug.c:587) full_proxy_release+0x67/0x90 (?:?) __fput+0x1df/0x4b0 (?:?) do_raw_spin_lock+0x10f/0x1b0 (?:?) fput_close_sync+0xd2/0x170 (?:?) __x64_sys_close+0x55/0x90 (?:?) do_syscall_64+0x10c/0x640 (arch/x86/entry/syscall_64.c:87) irqentry_exit+0xac/0x6e0 (?:?) 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+0x30f/0x580 (?:?) dlm_put+0x1ce/0x200 (?:?) dlm_unregister_domain+0xf6/0xb30 (?:?) o2cb_cluster_disconnect+0x6b/0x90 (?:?) ocfs2_cluster_disconnect+0x41/0x70 (?:?) ocfs2_dlm_shutdown+0x1c4/0x220 (?:?) ocfs2_dismount_volume+0x38a/0x550 (?:?) generic_shutdown_super+0xc3/0x220 (?:?) kill_block_super+0x29/0x60 (?:?) deactivate_locked_super+0x66/0xe0 (?:?) cleanup_mnt+0x13d/0x210 (?:?) task_work_run+0xfa/0x170 (?:?) exit_to_user_mode_loop+0xd6/0x430 (?:?) do_syscall_64+0x3cb/0x640 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)
{
"affected": [],
"aliases": [
"CVE-2026-74348"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T06:22:35Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2/dlm: require a ref for locking_state debugfs open\n\ndebug_lockres_open() copies inode-\u003ei_private into struct debug_lockres and\ndebug_lockres_release() later drops that pointer with dlm_put(). That\nonly works if open successfully pins the struct dlm_ctxt.\n\nToday open calls dlm_grab(dlm) but ignores its return value. Once the\nlast domain unregister has removed the context from dlm_domains,\ndlm_grab() returns NULL, yet open still stores the raw pointer and returns\nsuccess. The later release path is outside the debugfs removal barrier,\nso it can call dlm_put() after dlm_free_ctxt_mem() has freed the context. \nKASAN reports this as a slab-use-after-free in dlm_put() called from\ndebug_lockres_release().\n\nFail the open when dlm_grab() cannot acquire the reference and unwind the\nseq_file private state before returning. That keeps locking_state from\nhanding out a file descriptor whose release path does not own the\ndlm_ctxt.\n\nThe buggy scenario involves two paths, with each column showing the order\nwithin that path:\n\nlocking_state debugfs open: last domain unregister:\n1. debug_lockres_open() reads 1. dlm_unregister_domain() calls\n inode-\u003ei_private. dlm_complete_dlm_shutdown().\n2. debug_lockres_open() calls 2. shutdown removes the dlm_ctxt from\n dlm_grab(dlm) and gets NULL. dlm_domains.\n3. open still stores the raw dlm 3. final teardown reaches\n pointer in dl-\u003edl_ctxt and dlm_free_ctxt_mem() and frees it.\n returns success.\n4. debug_lockres_release() later\n calls dlm_put(dl-\u003edl_ctxt).\n\nValidation reproduced this kernel report:\nKASAN slab-use-after-free in dlm_put+0x82/0x200\nRIP: 0033:0x7f4d349bc9e0\nThe buggy address belongs to the object at ffff888103a3c000 which belongs\nto the cache kmalloc-2k of size 2048\nThe buggy address is located 816 bytes inside of freed 2048-byte region\n[ffff888103a3c000, ffff888103a3c800)\nWrite of size 4\nCall trace:\n dump_stack_lvl+0x66/0xa0 (?:?)\n print_report+0xd0/0x630 (?:?)\n dlm_put+0x82/0x200 (?:?)\n srso_alias_return_thunk+0x5/0xfbef5 (?:?)\n __virt_addr_valid+0x188/0x2f0 (?:?)\n kasan_report+0xe4/0x120 (?:?)\n kasan_check_range+0x105/0x1b0 (?:?)\n debug_lockres_release+0x53/0x80 (fs/ocfs2/dlm/dlmdebug.c:587)\n dlm_put+0x9/0x200 (?:?)\n debug_lockres_release+0x5c/0x80 (fs/ocfs2/dlm/dlmdebug.c:587)\n full_proxy_release+0x67/0x90 (?:?)\n __fput+0x1df/0x4b0 (?:?)\n do_raw_spin_lock+0x10f/0x1b0 (?:?)\n fput_close_sync+0xd2/0x170 (?:?)\n __x64_sys_close+0x55/0x90 (?:?)\n do_syscall_64+0x10c/0x640 (arch/x86/entry/syscall_64.c:87)\n irqentry_exit+0xac/0x6e0 (?:?)\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+0x30f/0x580 (?:?)\n dlm_put+0x1ce/0x200 (?:?)\n dlm_unregister_domain+0xf6/0xb30 (?:?)\n o2cb_cluster_disconnect+0x6b/0x90 (?:?)\n ocfs2_cluster_disconnect+0x41/0x70 (?:?)\n ocfs2_dlm_shutdown+0x1c4/0x220 (?:?)\n ocfs2_dismount_volume+0x38a/0x550 (?:?)\n generic_shutdown_super+0xc3/0x220 (?:?)\n kill_block_super+0x29/0x60 (?:?)\n deactivate_locked_super+0x66/0xe0 (?:?)\n cleanup_mnt+0x13d/0x210 (?:?)\n task_work_run+0xfa/0x170 (?:?)\n exit_to_user_mode_loop+0xd6/0x430 (?:?)\n do_syscall_64+0x3cb/0x640 (arch/x86/entry/syscall_64.c:87)\n entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)",
"id": "GHSA-7r62-vjjf-3924",
"modified": "2026-08-15T06:32:30Z",
"published": "2026-08-15T06:32:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74348"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/03ad858ce8064861ea580021976dc19b7aabb549"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5bee5d5f67aedd26d2b72e00e49dd93331fbcc30"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6cc93dea4078cbcddee63fa2234e382a76600464"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/90a6512425414098a63fc97b77bed089c75d106b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9c81c1a61a52b6ecf0d14f1dbd95f154a7a9e92a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a087b2d3411e7f9df71ba3293596923ee2c70d65"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a09831214912a1f270663d935613910fafd8d883"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/aa7883b6a3c76301a3299deb34de948e73bb6a08"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
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