CVE-2025-40028
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-10-28

Last updated on: 2025-10-30

Assigner: kernel.org

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().
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Meta Information
Published
2025-10-28
Last Modified
2025-10-30
Generated
2026-06-16
AI Q&A
2025-10-28
EPSS Evaluated
2026-06-15
NVD
CVE-2025-40028
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Showing 1 associated CPE
Vendor Product Version / Range
linux kernel *
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CWE ID Description
CWE-UNKNOWN
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Executive Summary

This vulnerability is a double-free error in the Linux kernel's binder driver. When a process tries to expand its proc->dmap bitmap but fails to allocate a new one, the old bitmap is freed. However, the driver frees the same bitmap again when the process terminates, causing a double-free. This can lead to memory corruption or kernel crashes. The issue is fixed by marking proc->map as NULL after freeing it to prevent the second free.

Impact Analysis

This vulnerability can cause kernel memory corruption or crashes due to the double-free error. This may lead to system instability, denial of service, or potentially allow an attacker to execute arbitrary code with kernel privileges.

Mitigation Strategies

The vulnerability is fixed by updating the Linux kernel to a version where the binder driver properly marks proc->map as NULL in dbitmap_free(), preventing the double-free error. Therefore, the immediate mitigation step is to apply the kernel patch or upgrade to a fixed kernel version that includes this fix.

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