{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-40028","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-04-16T07:20:57.152Z","datePublished":"2025-10-28T09:32:35.681Z","dateUpdated":"2026-08-05T12:07:10.905Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:07:10.905Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbinder: fix double-free in dbitmap\n\nA process might fail to allocate a new bitmap when trying to expand its\nproc->dmap. In that case, dbitmap_grow() fails and frees the old bitmap\nvia dbitmap_free(). However, the driver calls dbitmap_free() again when\nthe same process terminates, leading to a double-free error:\n\n  ==================================================================\n  BUG: KASAN: double-free in binder_proc_dec_tmpref+0x2e0/0x55c\n  Free of addr ffff00000b7c1420 by task kworker/9:1/209\n\n  CPU: 9 UID: 0 PID: 209 Comm: kworker/9:1 Not tainted 6.17.0-rc6-dirty #5 PREEMPT\n  Hardware name: linux,dummy-virt (DT)\n  Workqueue: events binder_deferred_func\n  Call trace:\n   kfree+0x164/0x31c\n   binder_proc_dec_tmpref+0x2e0/0x55c\n   binder_deferred_func+0xc24/0x1120\n   process_one_work+0x520/0xba4\n  [...]\n\n  Allocated by task 448:\n   __kmalloc_noprof+0x178/0x3c0\n   bitmap_zalloc+0x24/0x30\n   binder_open+0x14c/0xc10\n  [...]\n\n  Freed by task 449:\n   kfree+0x184/0x31c\n   binder_inc_ref_for_node+0xb44/0xe44\n   binder_transaction+0x29b4/0x7fbc\n   binder_thread_write+0x1708/0x442c\n   binder_ioctl+0x1b50/0x2900\n  [...]\n  ==================================================================\n\nFix this issue by marking proc->map NULL in dbitmap_free()."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The bug is reached only through `ioctl()`/`write()` on a binder character device (`/dev/binder` or a binderfs device node), requiring a local process on the system. There is no remote or network-facing path into `binder_transaction()`.\nAC:L - The attacker fully controls both preconditions: the size of the failing `bitmap_zalloc()` (by creating hundreds of thousands of binder references so the doubling bitmap enters costly-order allocations that fail without invoking the OOM killer) and the memory pressure/fragmentation that makes it fail, then chooses exactly when the second free occurs by closing the fd. The window between the two frees is arbitrarily long, making heap grooming reliable.\nPR:L - Binder contains no `capable()` checks at all on this path; on Android every unprivileged app can open a binder device, and on distro kernels with CONFIG_ANDROID_BINDERFS an unprivileged user can mount binderfs inside a user namespace (`FS_USERNS_MOUNT`) and create devices without any capability. Only a basic local account is needed.\nUI:N - The attacking process performs everything itself — open the device, drive transactions to grow the bitmap, exhaust memory, then close the fd. No victim action is involved.\nS:U - The corruption is confined to the kernel's own heap/page allocator within the same security authority; there is no VM, IOMMU, or hypervisor boundary crossed.\nC:H - The double free lets the attacker reclaim the chunk with a chosen object and then have the kernel free it while still in use, producing a use-after-free with overlapping allocations that can be leveraged to read arbitrary kernel memory (credentials, keys, KASLR data).\nI:H - Freeing an in-use, attacker-sprayed object (or a costly-order page, giving cross-cache/physical-page reuse) yields a write primitive over kernel objects, enabling control-flow hijack and privilege escalation to root.\nA:H - Even unweaponized, the double free corrupts the SLUB freelist or page allocator and reliably panics the kernel (KASAN reports it as a `double-free` BUG), and the attacker can repeat it across many binder fds."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/android/dbitmap.h"],"versions":[{"version":"15d9da3f818cae676f822a04407d3c17b53357d2","lessThan":"c301ec61ce6f16e21a36b99225ca8a20c1591e10","status":"affected","versionType":"git"},{"version":"15d9da3f818cae676f822a04407d3c17b53357d2","lessThan":"0390633979969c54c0ce6a198d6f45cdbe2c84b1","status":"affected","versionType":"git"},{"version":"15d9da3f818cae676f822a04407d3c17b53357d2","lessThan":"b781e5635a3398e2b64440371233c2c5102cd6cb","status":"affected","versionType":"git"},{"version":"15d9da3f818cae676f822a04407d3c17b53357d2","lessThan":"3ebcd3460cad351f198c39c6edb4af519a0ed934","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/android/dbitmap.h"],"versions":[{"version":"6.11","status":"affected"},{"version":"0","lessThan":"6.11","status":"unaffected","versionType":"semver"},{"version":"6.12.52","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.16.12","lessThanOrEqual":"6.16.*","status":"unaffected","versionType":"semver"},{"version":"6.17.2","lessThanOrEqual":"6.17.*","status":"unaffected","versionType":"semver"},{"version":"6.18","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.12.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.16.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.17.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.18"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/c301ec61ce6f16e21a36b99225ca8a20c1591e10"},{"url":"https://git.kernel.org/stable/c/0390633979969c54c0ce6a198d6f45cdbe2c84b1"},{"url":"https://git.kernel.org/stable/c/b781e5635a3398e2b64440371233c2c5102cd6cb"},{"url":"https://git.kernel.org/stable/c/3ebcd3460cad351f198c39c6edb4af519a0ed934"}],"title":"binder: fix double-free in dbitmap","x_generator":{"engine":"bippy-1.2.0"}}}}