| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2023-52438: binder: fix use-after-free in shinker's callback |
| |
| Description |
| =========== |
| |
| 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. |
| |
| The Linux kernel CVE team has assigned CVE-2023-52438 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.20 with commit dd2283f2605e3b3e9c61bcae844b34f2afa4813f and fixed in 5.4.268 with commit a53e15e592b4dcc91c3a3b8514e484a0bdbc53a3 |
| Issue introduced in 4.20 with commit dd2283f2605e3b3e9c61bcae844b34f2afa4813f and fixed in 5.10.209 with commit c8c1158ffb007197f31f9d9170cf13e4f34cbb5c |
| Issue introduced in 4.20 with commit dd2283f2605e3b3e9c61bcae844b34f2afa4813f and fixed in 5.15.148 with commit 8ad4d580e8aff8de2a4d57c5930fcc29f1ffd4a6 |
| Issue introduced in 4.20 with commit dd2283f2605e3b3e9c61bcae844b34f2afa4813f and fixed in 6.1.74 with commit 9fa04c93f24138747807fe75b5591bb680098f56 |
| Issue introduced in 4.20 with commit dd2283f2605e3b3e9c61bcae844b34f2afa4813f and fixed in 6.6.13 with commit a49087ab93508b60d9b8add91707a22dda832869 |
| Issue introduced in 4.20 with commit dd2283f2605e3b3e9c61bcae844b34f2afa4813f and fixed in 6.7.1 with commit e074686e993ff1be5f21b085a3b1b4275ccd5727 |
| Issue introduced in 4.20 with commit dd2283f2605e3b3e9c61bcae844b34f2afa4813f and fixed in 6.8 with commit 3f489c2067c5824528212b0fc18b28d51332d906 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2023-52438 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| drivers/android/binder_alloc.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/a53e15e592b4dcc91c3a3b8514e484a0bdbc53a3 |
| https://git.kernel.org/stable/c/c8c1158ffb007197f31f9d9170cf13e4f34cbb5c |
| https://git.kernel.org/stable/c/8ad4d580e8aff8de2a4d57c5930fcc29f1ffd4a6 |
| https://git.kernel.org/stable/c/9fa04c93f24138747807fe75b5591bb680098f56 |
| https://git.kernel.org/stable/c/a49087ab93508b60d9b8add91707a22dda832869 |
| https://git.kernel.org/stable/c/e074686e993ff1be5f21b085a3b1b4275ccd5727 |
| https://git.kernel.org/stable/c/3f489c2067c5824528212b0fc18b28d51332d906 |
