# CVE-2022-49947: linux: In the Linux kernel, the following vulnerability has been resolved:  binder: fix alloc->vma_vm_mm null-ptr dereferenc...

CVE-2022-49947 is fixed in linux on 1 platform, first by DEBIAN-CVE-2022-49947, released June 18, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-49947
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0023
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 18, 2025

## Description

In the Linux kernel, the following vulnerability has been resolved:  binder: fix alloc->vma_vm_mm null-ptr dereference  Syzbot reported a couple issues introduced by commit 44e602b4e52f ("binder_alloc: add missing mmap_lock calls when using the VMA"), in which we attempt to acquire the mmap_lock when alloc->vma_vm_mm has not been initialized yet.  This can happen if a binder_proc receives a transaction without having previously called mmap() to setup the binder_proc->alloc space in [1]. Also, a similar issue occurs via binder_alloc_print_pages() when we try to dump the debugfs binder stats file in [2].  Sample of syzbot's crash report:   ==================================================================   KASAN: null-ptr-deref in range [0x0000000000000128-0x000000000000012f]   CPU: 0 PID: 3755 Comm: syz-executor229 Not tainted 6.0.0-rc1-next-20220819-syzkaller #0   syz-executor229[3755] cmdline: ./syz-executor2294415195   Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022   RIP: 0010:__lock_acquire+0xd83/0x56d0 kernel/locking/lockdep.c:4923   [...]   Call Trace:    <TASK>    lock_acquire kernel/locking/lockdep.c:5666 [inline]    lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631    down_read+0x98/0x450 kernel/locking/rwsem.c:1499    mmap_read_lock include/linux/mmap_lock.h:117 [inline]    binder_alloc_new_buf_locked drivers/android/binder_alloc.c:405 [inline]    binder_alloc_new_buf+0xa5/0x19e0 drivers/android/binder_alloc.c:593    binder_transaction+0x242e/0x9a80 drivers/android/binder.c:3199    binder_thread_write+0x664/0x3220 drivers/android/binder.c:3986    binder_ioctl_write_read drivers/android/binder.c:5036 [inline]    binder_ioctl+0x3470/0x6d00 drivers/android/binder.c:5323    vfs_ioctl fs/ioctl.c:51 [inline]    __do_sys_ioctl fs/ioctl.c:870 [inline]    __se_sys_ioctl fs/ioctl.c:856 [inline]    __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856    do_syscall_x64 arch/x86/entry/common.c:50 [inline]    do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80    entry_SYSCALL_64_after_hwframe+0x63/0xcd    [...]   ==================================================================  Fix these issues by setting up alloc->vma_vm_mm pointer during open() and caching directly from current->mm. This guarantees we have a valid reference to take the mmap_lock during scenarios described above.  [1] https://syzkaller.appspot.com/bug?extid=f7dc54e5be28950ac459 [2] https://syzkaller.appspot.com/bug?extid=a75ebe0452711c9e56d9

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.0.2-1 | [DEBIAN-CVE-2022-49947](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49947.md) | Jun 18, 2025 |
| Linux | linux Debian 13.5 (trixie) | 6.0.2-1 | [DEBIAN-CVE-2022-49947](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49947.md) | Jun 18, 2025 |
| Linux | linux Debian 14 | 6.0.2-1 | [DEBIAN-CVE-2022-49947](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49947.md) | Jun 18, 2025 |

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