Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: binder: fix double-free in dbitmap A process might fail to allocate a new bitmap… (CVE-2025-40028)
In the Linux kernel, the following vulnerability has been resolved: binder: fix double-free in dbitmap A process might fail to allocate a new bitmap when trying to expand its proc->dmap. In that case, dbitmap_grow() fails and frees the old bitmap via dbitmap_free(). However, the driver calls dbitmap_free() again when the same process terminates, leading to a double-free error: ================================================================== BUG: KASAN: double-free in binder_proc_dec_tmpref+0x2e0/0x55c Free of addr ffff00000b7c1420 by task kworker/9:1/209 CPU: 9 UID: 0 PID: 209 Comm: kworker/9:1 Not tainted 6.17.0-rc6-dirty #5 PREEMPT Hardware name: linux,dummy-virt (DT) Workqueue: events binder_deferred_func Call trace: kfree+0x164/0x31c binder_proc_dec_tmpref+0x2e0/0x55c binder_deferred_func+0xc24/0x1120 process_one_work+0x520/0xba4 [...] Allocated by task 448: __kmalloc_noprof+0x178/0x3c0 bitmap_zalloc+0x24/0x30 binder_open+0x14c/0xc10 [...] Freed by task 449: kfree+0x184/0x31c binder_inc_ref_for_node+0xb44/0xe44 binder_transaction+0x29b4/0x7fbc binder_thread_write+0x1708/0x442c binder_ioctl+0x1b50/0x2900 [...] ================================================================== Fix this issue by marking proc->map NULL in dbitmap_free().
AI Analysis
Technical Summary
The Linux kernel binder driver contained a double-free vulnerability (CVE-2025-40028) in the dbitmap management. When a process attempts to expand its proc->dmap bitmap and allocation fails, dbitmap_grow() frees the old bitmap. However, the driver also frees this bitmap again upon process termination, resulting in a double-free error detected by KASAN. The fix involves marking proc->map as NULL in dbitmap_free() to prevent the second free call.
Potential Impact
The double-free vulnerability can lead to kernel memory corruption, which may cause system crashes, denial of service, or potentially privilege escalation due to corrupted kernel memory management. The CVSS vector indicates local attack vector with low complexity, requiring low privileges, no user interaction, and impacts confidentiality, integrity, and availability at a high level.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. The issue is fixed by marking proc->map NULL in dbitmap_free(), so applying the official Linux kernel updates that include this fix is recommended once available.
Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: binder: fix double-free in dbitmap A process might fail to allocate a new bitmap… (CVE-2025-40028)
Description
In the Linux kernel, the following vulnerability has been resolved: binder: fix double-free in dbitmap A process might fail to allocate a new bitmap when trying to expand its proc->dmap. In that case, dbitmap_grow() fails and frees the old bitmap via dbitmap_free(). However, the driver calls dbitmap_free() again when the same process terminates, leading to a double-free error: ================================================================== BUG: KASAN: double-free in binder_proc_dec_tmpref+0x2e0/0x55c Free of addr ffff00000b7c1420 by task kworker/9:1/209 CPU: 9 UID: 0 PID: 209 Comm: kworker/9:1 Not tainted 6.17.0-rc6-dirty #5 PREEMPT Hardware name: linux,dummy-virt (DT) Workqueue: events binder_deferred_func Call trace: kfree+0x164/0x31c binder_proc_dec_tmpref+0x2e0/0x55c binder_deferred_func+0xc24/0x1120 process_one_work+0x520/0xba4 [...] Allocated by task 448: __kmalloc_noprof+0x178/0x3c0 bitmap_zalloc+0x24/0x30 binder_open+0x14c/0xc10 [...] Freed by task 449: kfree+0x184/0x31c binder_inc_ref_for_node+0xb44/0xe44 binder_transaction+0x29b4/0x7fbc binder_thread_write+0x1708/0x442c binder_ioctl+0x1b50/0x2900 [...] ================================================================== Fix this issue by marking proc->map NULL in dbitmap_free().
CVSS v3.1
Score 7.8high
Affected software
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel binder driver contained a double-free vulnerability (CVE-2025-40028) in the dbitmap management. When a process attempts to expand its proc->dmap bitmap and allocation fails, dbitmap_grow() frees the old bitmap. However, the driver also frees this bitmap again upon process termination, resulting in a double-free error detected by KASAN. The fix involves marking proc->map as NULL in dbitmap_free() to prevent the second free call.
Potential Impact
The double-free vulnerability can lead to kernel memory corruption, which may cause system crashes, denial of service, or potentially privilege escalation due to corrupted kernel memory management. The CVSS vector indicates local attack vector with low complexity, requiring low privileges, no user interaction, and impacts confidentiality, integrity, and availability at a high level.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. The issue is fixed by marking proc->map NULL in dbitmap_free(), so applying the official Linux kernel updates that include this fix is recommended once available.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-8vjm-fc8f-c7jh
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2025-40028"]
- Database Specific Severity
- HIGH
- Cvss Version
- 3.1
Threat ID: 6a6b72d79c2644c7f847b7e1
Added to database: 07/30/2026, 15:50:47 UTC
Last enriched: 07/30/2026, 15:57:53 UTC
Last updated: 09/10/2026, 19:36:50 UTC
Views: 16
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