kernel/linux.git/drivers/android, branch v5.4.269

binder: signal epoll threads of self-work

2024-02-23T07:25:11+00:00

commit 97830f3c3088638ff90b20dfba2eb4d487bf14d7 upstream. In (e)poll mode, threads often depend on I/O events to determine when data is ready for consumption. Within binder, a thread may initiate a command via BINDER_WRITE_READ without a read buffer and then make use of epoll_wait() or similar to consume any responses afterwards. It is then crucial that epoll threads are signaled via wakeup when they queue their own work. Otherwise, they risk waiting indefinitely for an event leaving their work unhandled. What is worse, subsequent commands won't trigger a wakeup either as the thread has pending work. Fixes: 457b9a6f09f0 ("Staging: android: add binder driver") Cc: Arve Hjønnevåg Cc: Martijn Coenen Cc: Alice Ryhl Cc: Steven Moreland Cc: stable@vger.kernel.org # v4.19+ Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20240131215347.1808751-1-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman

binder: fix unused alloc->free_async_space

2024-01-25T22:34:29+00:00

commit c6d05e0762ab276102246d24affd1e116a46aa0c upstream. Each transaction is associated with a 'struct binder_buffer' that stores the metadata about its buffer area. Since commit 74310e06be4d ("android: binder: Move buffer out of area shared with user space") this struct is no longer embedded within the buffer itself but is instead allocated on the heap to prevent userspace access to this driver-exclusive info. Unfortunately, the space of this struct is still being accounted for in the total buffer size calculation, specifically for async transactions. This results in an additional 104 bytes added to every async buffer request, and this area is never used. This wasted space can be substantial. If we consider the maximum mmap buffer space of SZ_4M, the driver will reserve half of it for async transactions, or 0x200000. This area should, in theory, accommodate up to 262,144 buffers of the minimum 8-byte size. However, after adding the extra 'sizeof(struct binder_buffer)', the total number of buffers drops to only 18,724, which is a sad 7.14% of the actual capacity. This patch fixes the buffer size calculation to enable the utilization of the entire async buffer space. This is expected to reduce the number of -ENOSPC errors that are seen on the field. Fixes: 74310e06be4d ("android: binder: Move buffer out of area shared with user space") Signed-off-by: Carlos Llamas Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20231201172212.1813387-6-cmllamas@google.com [cmllamas: fix trivial conflict with missing 261e7818f06e.] Signed-off-by: Carlos Llamas Signed-off-by: Greg Kroah-Hartman

binder: fix race between mmput() and do_exit()

2024-01-25T22:34:29+00:00

commit 9a9ab0d963621d9d12199df9817e66982582d5a5 upstream. Task A calls binder_update_page_range() to allocate and insert pages on a remote address space from Task B. For this, Task A pins the remote mm via mmget_not_zero() first. This can race with Task B do_exit() and the final mmput() refcount decrement will come from Task A. Task A | Task B ------------------+------------------ mmget_not_zero() | | do_exit() | exit_mm() | mmput() mmput() | exit_mmap() | remove_vma() | fput() | In this case, the work of ____fput() from Task B is queued up in Task A as TWA_RESUME. So in theory, Task A returns to userspace and the cleanup work gets executed. However, Task A instead sleep, waiting for a reply from Task B that never comes (it's dead). This means the binder_deferred_release() is blocked until an unrelated binder event forces Task A to go back to userspace. All the associated death notifications will also be delayed until then. In order to fix this use mmput_async() that will schedule the work in the corresponding mm->async_put_work WQ instead of Task A. Fixes: 457b9a6f09f0 ("Staging: android: add binder driver") Reviewed-by: Alice Ryhl Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20231201172212.1813387-4-cmllamas@google.com [cmllamas: fix trivial conflict with missing d8ed45c5dcd4.] Signed-off-by: Carlos Llamas Signed-off-by: Greg Kroah-Hartman

binder: fix use-after-free in shinker's callback

2024-01-25T22:34:29+00:00

commit 3f489c2067c5824528212b0fc18b28d51332d906 upstream. 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. Fixes: dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap") Cc: stable@vger.kernel.org Cc: Liam Howlett Cc: Minchan Kim Reviewed-by: Alice Ryhl Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20231201172212.1813387-3-cmllamas@google.com [cmllamas: use find_vma() instead of vma_lookup() as commit ce6d42f2e4a2 is missing in v5.4. This only works because we check the vma against our cached alloc->vma pointer. Also, unlock via up_read() instead of mmap_read_unlock() as commit d8ed45c5dcd4 is also missing in v5.4.] Signed-off-by: Carlos Llamas Signed-off-by: Greg Kroah-Hartman

binder: fix async space check for 0-sized buffers

2024-01-25T22:34:29+00:00

commit 3091c21d3e9322428691ce0b7a0cfa9c0b239eeb upstream. Move the padding of 0-sized buffers to an earlier stage to account for this round up during the alloc->free_async_space check. Fixes: 74310e06be4d ("android: binder: Move buffer out of area shared with user space") Reviewed-by: Alice Ryhl Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20231201172212.1813387-5-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman

binder: fix comment on binder_alloc_new_buf() return value

2024-01-25T22:34:21+00:00

commit e1090371e02b601cbfcea175c2a6cc7c955fa830 upstream. Update the comments of binder_alloc_new_buf() to reflect that the return value of the function is now ERR_PTR(-errno) on failure. No functional changes in this patch. Cc: stable@vger.kernel.org Fixes: 57ada2fb2250 ("binder: add log information for binder transaction failures") Reviewed-by: Alice Ryhl Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20231201172212.1813387-8-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman

binder: fix trivial typo of binder_free_buf_locked()

2024-01-25T22:34:21+00:00

commit 122a3c1cb0ff304c2b8934584fcfea4edb2fe5e3 upstream. Fix minor misspelling of the function in the comment section. No functional changes in this patch. Cc: stable@vger.kernel.org Fixes: 0f966cba95c7 ("binder: add flag to clear buffer on txn complete") Reviewed-by: Alice Ryhl Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20231201172212.1813387-7-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman

binder: use EPOLLERR from eventpoll.h

2024-01-25T22:34:21+00:00

commit 6ac061db9c58ca5b9270b1b3940d2464fb3ff183 upstream. Use EPOLLERR instead of POLLERR to make sure it is cast to the correct __poll_t type. This fixes the following sparse issue: drivers/android/binder.c:5030:24: warning: incorrect type in return expression (different base types) drivers/android/binder.c:5030:24: expected restricted __poll_t drivers/android/binder.c:5030:24: got int Fixes: f88982679f54 ("binder: check for binder_thread allocation failure in binder_poll()") Cc: stable@vger.kernel.org Cc: Eric Biggers Reviewed-by: Alice Ryhl Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20231201172212.1813387-2-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman

binder: fix memory leak in binder_init()

2023-08-16T16:19:23+00:00

commit adb9743d6a08778b78d62d16b4230346d3508986 upstream. In binder_init(), the destruction of binder_alloc_shrinker_init() is not performed in the wrong path, which will cause memory leaks. So this commit introduces binder_alloc_shrinker_exit() and calls it in the wrong path to fix that. Signed-off-by: Qi Zheng Acked-by: Carlos Llamas Fixes: f2517eb76f1f ("android: binder: Add global lru shrinker to binder") Cc: stable Link: https://lore.kernel.org/r/20230625154937.64316-1-qi.zheng@linux.dev Signed-off-by: Greg Kroah-Hartman

binder: fix UAF caused by faulty buffer cleanup

2023-06-05T06:17:33+00:00

commit bdc1c5fac982845a58d28690cdb56db8c88a530d upstream. In binder_transaction_buffer_release() the 'failed_at' offset indicates the number of objects to clean up. However, this function was changed by commit 44d8047f1d87 ("binder: use standard functions to allocate fds"), to release all the objects in the buffer when 'failed_at' is zero. This introduced an issue when a transaction buffer is released without any objects having been processed so far. In this case, 'failed_at' is indeed zero yet it is misinterpreted as releasing the entire buffer. This leads to use-after-free errors where nodes are incorrectly freed and subsequently accessed. Such is the case in the following KASAN report: ================================================================== BUG: KASAN: slab-use-after-free in binder_thread_read+0xc40/0x1f30 Read of size 8 at addr ffff4faf037cfc58 by task poc/474 CPU: 6 PID: 474 Comm: poc Not tainted 6.3.0-12570-g7df047b3f0aa #5 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x94/0xec show_stack+0x18/0x24 dump_stack_lvl+0x48/0x60 print_report+0xf8/0x5b8 kasan_report+0xb8/0xfc __asan_load8+0x9c/0xb8 binder_thread_read+0xc40/0x1f30 binder_ioctl+0xd9c/0x1768 __arm64_sys_ioctl+0xd4/0x118 invoke_syscall+0x60/0x188 [...] Allocated by task 474: kasan_save_stack+0x3c/0x64 kasan_set_track+0x2c/0x40 kasan_save_alloc_info+0x24/0x34 __kasan_kmalloc+0xb8/0xbc kmalloc_trace+0x48/0x5c binder_new_node+0x3c/0x3a4 binder_transaction+0x2b58/0x36f0 binder_thread_write+0x8e0/0x1b78 binder_ioctl+0x14a0/0x1768 __arm64_sys_ioctl+0xd4/0x118 invoke_syscall+0x60/0x188 [...] Freed by task 475: kasan_save_stack+0x3c/0x64 kasan_set_track+0x2c/0x40 kasan_save_free_info+0x38/0x5c __kasan_slab_free+0xe8/0x154 __kmem_cache_free+0x128/0x2bc kfree+0x58/0x70 binder_dec_node_tmpref+0x178/0x1fc binder_transaction_buffer_release+0x430/0x628 binder_transaction+0x1954/0x36f0 binder_thread_write+0x8e0/0x1b78 binder_ioctl+0x14a0/0x1768 __arm64_sys_ioctl+0xd4/0x118 invoke_syscall+0x60/0x188 [...] ================================================================== In order to avoid these issues, let's always calculate the intended 'failed_at' offset beforehand. This is renamed and wrapped in a helper function to make it clear and convenient. Fixes: 32e9f56a96d8 ("binder: don't detect sender/target during buffer cleanup") Reported-by: Zi Fan Tan Cc: stable@vger.kernel.org Signed-off-by: Carlos Llamas Acked-by: Todd Kjos Link: https://lore.kernel.org/r/20230505203020.4101154-1-cmllamas@google.com [cmllamas: resolve trivial conflict due to missing commit 9864bb4801331] Signed-off-by: Carlos Llamas Signed-off-by: Greg Kroah-Hartman