概要

In the Linux kernel, the following vulnerability has been resolved:binder: fix UAF caused by offsets overwriteBinder objects are processed and copied individually into the targetbuffer during transactions. Any raw data in-between these objects iscopied as well. However, this raw data copy lacks an out-of-boundscheck. If the raw data exceeds the data section size then the copyoverwrites the offsets section. This eventually triggers an error thatattempts to unwind the processed objects. However, at this point theoffsets used to index these objects are now corrupted.Unwinding with corrupted offsets can result in decrements of arbitrarynodes and lead to their premature release. Other users of such nodes areleft with a dangling pointer triggering a use-after-free. This issue ismade evident by the following KASAN report (trimmed): ================================================================== BUG: KASAN: slab-use-after-free in _raw_spin_lock+0xe4/0x19c Write of size 4 at addr ffff47fc91598f04 by task binder-util/743 CPU: 9 UID: 0 PID: 743 Comm: binder-util Not tainted 6.11.0-rc4 #1 Hardware name: linux,dummy-virt (DT) Call trace: _raw_spin_lock+0xe4/0x19c binder_free_buf+0x128/0x434 binder_thread_write+0x8a4/0x3260 binder_ioctl+0x18f0/0x258c [...] Allocated by task 743: __kmalloc_cache_noprof+0x110/0x270 binder_new_node+0x50/0x700 binder_transaction+0x413c/0x6da8 binder_thread_write+0x978/0x3260 binder_ioctl+0x18f0/0x258c [...] Freed by task 745: kfree+0xbc/0x208 binder_thread_read+0x1c5c/0x37d4 binder_ioctl+0x16d8/0x258c [...] ==================================================================To avoid this issue, let s check that the raw data copy is within theboundaries of the data section.

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