binderfs: fix UAF write in binder_add_device
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EPSS probability
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Risk score
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Published
9 h ago
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Vulnerability description
CVE AI research
DayBreach AI Explanation
Verified against sourcesSources read
2
Source agreement
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Evidence confidence
%61
Short explanation
A use-after-free write vulnerability exists in the binderfs component of the Linux kernel within binder_add_device. This occurs because a concurrent unlinkat call can remove the device entry after locks are dropped, leading to access on a freed object.
Vulnerabilities of this nature can lead to memory corruption and kernel instability, threatening overall system security.
What should be done?
- Follow vendor advisories
- Apply relevant kernel patch versions
The sources give limited detail on some technical conditions. Review the chain of evidence below before deciding how to act.
Chain of evidence and sources
binderfs_binder_device_create() fonksiyonu simple_done_creating() çağrısı sonrasında kilitleri bırakır.
Eş zamanlı bir unlinkat() çağrısı yeni cihaz girdisini kaldırabilir.
binder_add_device() serbest bırakılmış nesneye erişerek UAF yazma durumuna yol açar.
Show the technical text from the sources
In the Linux kernel, the following vulnerability has been resolved: binderfs: fix UAF write in binder_add_device binderfs_binder_device_create() publishes the new dentry with d_make_persistent() and then calls simple_done_creating(), which drops the parent directory lock and the creator's dentry reference. It then calls binder_add_device() to register the device in the global binder_devices list. After simple_done_creating() releases the parent directory lock, a concurrent unlinkat() can remove the new device entry. Dropping the creator's dentry reference can then trigger binderfs_evict_inode(), freeing the device. binder_add_device() later accesses the freed object, causing UAF write. Found by a modified Syzkaller: BUG: KASAN: slab-use-after-free in hlist_add_head include/linux/list.h:1073 [inline] BUG: KASAN: slab-use-after-free in binder_add_device+0xa9/0xc0 drivers/android/binder.c:7068 Write of size 8 at addr ffff88805b340c00 by task syz.1.532/11389 CPU: 0 UID: 0 PID: 11389 Comm: syz.1.532 Not tainted 7.2.0 #4 PREEMPT(full) Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x10e/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xf7/0x600 mm/kasan/report.c:482 kasan_report+0xe4/0x120 mm/kasan/report.c:595 hlist_add_head include/linux/list.h:1073 [inline] binder_add_device+0xa9/0xc0 drivers/android/binder.c:7068 binderfs_binder_device_create.isra.0+0x724/0x990 drivers/android/binderfs.c:196 binder_ctl_ioctl+0x186/0x1b0 drivers/android/binderfs.c:241 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x116/0x800 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff9027a833d Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ff903674018 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ff902a35fa0 RCX: 00007ff9027a833d RDX: 0000200000000500 RSI: 00000000c1086201 RDI: 0000000000000004 RBP: 00007ff902850733 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ff902a36038 R14: 00007ff902a35fa0 R15: 00007ffd7166bfa0 </TASK> Allocated by task 11389: kasan_save_stack+0x33/0x60 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x2e4/0x6f0 mm/slub.c:5489 _kmalloc_noprof include/linux/slab.h:988 [inline] _kzalloc_noprof include/linux/slab.h:1309 [inline] binderfs_binder_device_create.isra.0+0x17a/0x990 drivers/android/binderfs.c:148 binder_ctl_ioctl+0x186/0x1b0 drivers/android/binderfs.c:241 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x116/0x800 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 11389: kasan_save_stack+0x33/0x60 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2677 [inline] slab_free mm/slub.c:6377 [inline] kfree+0x2fc/0x6e0 mm/slub.c:6692 binderf ---truncated---
Explanation produced with the local gemini-flash-lite-latest model. Numerical metrics and the KEV, patch and exploit statuses are not determined by AI.
IMPACT: Affected Products and Software
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
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Patch and Remediation Guide
Solution & Remediation Advisory
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Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-98776 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-98776 weaknesses.
Official Sources and Advisories
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