CVE-2022-49939
binder: fix UAF of ref->proc caused by race condition
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binder: fix UAF of ref->proc caused by race condition
In the Linux kernel, the following vulnerability has been resolved: binder: fix UAF of ref->proc caused by race condition A transaction of type BINDER_TYPE_WEAK_HANDLE can fail to increment the reference for a node. In this case, the target proc normally releases the failed reference upon close as expected. However, if the target is dying in parallel the call will race with binder_deferred_release(), so the target could have released all of its references by now leaving the cleanup of the new failed reference unhandled. The transaction then ends and the target proc gets released making the ref->proc now a dangling pointer. Later on, ref->node is closed and we attempt to take spin_lock(&ref->proc->inner_lock), which leads to the use-after-free bug reported below. Let's fix this by cleaning up the failed reference on the spot instead of relying on the target to do so. ================================================================== BUG: KASAN: use-after-free in _raw_spin_lock+0xa8/0x150 Write of size 4 at addr ffff5ca207094238 by task kworker/1:0/590 CPU: 1 PID: 590 Comm: kworker/1:0 Not tainted 5.19.0-rc8 #10 Hardware name: linux,dummy-virt (DT) Workqueue: events binder_deferred_func Call trace: dump_backtrace.part.0+0x1d0/0x1e0 show_stack+0x18/0x70 dump_stack_lvl+0x68/0x84 print_report+0x2e4/0x61c kasan_report+0xa4/0x110 kasan_check_range+0xfc/0x1a4 __kasan_check_write+0x3c/0x50 _raw_spin_lock+0xa8/0x150 binder_deferred_func+0x5e0/0x9b0 process_one_work+0x38c/0x5f0 worker_thread+0x9c/0x694 kthread+0x188/0x190 ret_from_fork+0x10/0x20
Reserved 2025-05-01 | Published 2025-06-18 | Updated 2025-06-18 | Assigner Linuxgit.kernel.org/...c/229f47603dd306bc0eb1a831439adb8e48bb0eae
git.kernel.org/...c/06e5b43ca4dab06a92bf4c2f33766e6fb11b880a
git.kernel.org/...c/30d0901b307f27d36b2655fb3048cf31ee0e89c0
git.kernel.org/...c/9629f2dfdb1dad294b468038ff8e161e94d0b609
git.kernel.org/...c/c2a4b5dc8fa71af73bab704d0cac42ac39767ed6
git.kernel.org/...c/603a47f2ae56bf68288784d3c0a8c5b8e0a827ed
git.kernel.org/...c/a0e44c64b6061dda7e00b7c458e4523e2331b739
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