{"uuid": "c7598489-e582-4257-a763-61c0818547d1", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2023-52438", "type": "seen", "source": "https://t.me/arpsyndicate/3837", "content": "#ExploitObserverAlert\n\nCVE-2023-52438\n\nDESCRIPTION: Exploit Observer has 1 entries in 1 file formats related to CVE-2023-52438. In the Linux kernel, the following vulnerability has been resolved:  binder: fix use-after-free in shinker's callback  The mmap read lock is used during the shrinker's callback, which means that using alloc->vma pointer isn't safe as it can race with munmap(). As of commit dd2283f2605e (\"mm: mmap: zap pages with read mmap_sem in munmap\") the mmap lock is downgraded after the vma has been isolated.  I was able to reproduce this issue by manually adding some delays and triggering page reclaiming through the shrinker's debug sysfs. The following KASAN report confirms the UAF:    ==================================================================   BUG: KASAN: slab-use-after-free in zap_page_range_single+0x470/0x4b8   Read of size 8 at addr ffff356ed50e50f0 by task bash/478    CPU: 1 PID: 478 Comm: bash Not tainted 6.6.0-rc5-00055-g1c8b86a3799f-dirty #70   Hardware name: linux,dummy-virt (DT)   Call trace:    zap_page_range_single+0x470/0x4b8    binder_alloc_free_page+0x608/0xadc    __list_lru_walk_one+0x130/0x3b0    list_lru_walk_node+0xc4/0x22c    binder_shrink_scan+0x108/0x1dc    shrinker_debugfs_scan_write+0x2b4/0x500    full_proxy_write+0xd4/0x140    vfs_write+0x1ac/0x758    ksys_write+0xf0/0x1dc    __arm64_sys_write+0x6c/0x9c    Allocated by task 492:    kmem_cache_alloc+0x130/0x368    vm_area_alloc+0x2c/0x190    mmap_region+0x258/0x18bc    do_mmap+0x694/0xa60    vm_mmap_pgoff+0x170/0x29c    ksys_mmap_pgoff+0x290/0x3a0    __arm64_sys_mmap+0xcc/0x144    Freed by task 491:    kmem_cache_free+0x17c/0x3c8    vm_area_free_rcu_cb+0x74/0x98    rcu_core+0xa38/0x26d4    rcu_core_si+0x10/0x1c    __do_softirq+0x2fc/0xd24    Last potentially related work creation:    __call_rcu_common.constprop.0+0x6c/0xba0    call_rcu+0x10/0x1c    vm_area_free+0x18/0x24    remove_vma+0xe4/0x118    do_vmi_align_munmap.isra.0+0x718/0xb5c    do_vmi_munmap+0xdc/0x1fc    __vm_munmap+0x10c/0x278    __arm64_sys_munmap+0x58/0x7c  Fix this issue by performing instead a vma_lookup() which will fail to find the vma that was isolated before the mmap lock downgrade. Note that this option has better performance than upgrading to a mmap write lock which would increase contention. Plus, mmap_write_trylock() has been recently removed anyway.", "creation_timestamp": "2024-02-21T15:17:01.000000Z"}