user/sven/linux.git/drivers/android, branch v5.4.253

binder: fix UAF caused by faulty buffer cleanup

2023-06-05T06:17:33Z

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

binder: Gracefully handle BINDER_TYPE_FDA objects with num_fds=0

2022-12-08T10:23:01Z

commit ef38de9217a04c9077629a24652689d8fdb4c6c6 upstream. Some android userspace is sending BINDER_TYPE_FDA objects with num_fds=0. Like the previous patch, this is reproducible when playing a video. Before commit 09184ae9b575 BINDER_TYPE_FDA objects with num_fds=0 were 'correctly handled', as in no fixup was performed. After commit 09184ae9b575 we aggregate fixup and skip regions in binder_ptr_fixup structs and distinguish between the two by using the skip_size field: if it's 0, then it's a fixup, otherwise skip. When processing BINDER_TYPE_FDA objects with num_fds=0 we add a skip region of skip_size=0, and this causes issues because now binder_do_deferred_txn_copies will think this was a fixup region. To address that, return early from binder_translate_fd_array to avoid adding an empty skip region. Fixes: 09184ae9b575 ("binder: defer copies of pre-patched txn data") Acked-by: Todd Kjos Cc: stable Signed-off-by: Alessandro Astone Link: https://lore.kernel.org/r/20220415120015.52684-1-ales.astone@gmail.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Carlos Llamas Signed-off-by: Greg Kroah-Hartman

binder: Address corner cases in deferred copy and fixup

2022-12-08T10:23:01Z

commit 2d1746e3fda0c3612143d7c06f8e1d1830c13e23 upstream. When handling BINDER_TYPE_FDA object we are pushing a parent fixup with a certain skip_size but no scatter-gather copy object, since the copy is handled standalone. If BINDER_TYPE_FDA is the last children the scatter-gather copy loop will never stop to skip it, thus we are left with an item in the parent fixup list. This will trigger the BUG_ON(). This is reproducible in android when playing a video. We receive a transaction that looks like this: obj[0] BINDER_TYPE_PTR, parent obj[1] BINDER_TYPE_PTR, child obj[2] BINDER_TYPE_PTR, child obj[3] BINDER_TYPE_FDA, child Fixes: 09184ae9b575 ("binder: defer copies of pre-patched txn data") Acked-by: Todd Kjos Cc: stable Signed-off-by: Alessandro Astone Link: https://lore.kernel.org/r/20220415120015.52684-2-ales.astone@gmail.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Carlos Llamas Signed-off-by: Greg Kroah-Hartman

binder: fix pointer cast warning

2022-12-08T10:23:01Z

commit 9a0a930fe2535a76ad70d3f43caeccf0d86a3009 upstream. binder_uintptr_t is not the same as uintptr_t, so converting it into a pointer requires a second cast: drivers/android/binder.c: In function 'binder_translate_fd_array': drivers/android/binder.c:2511:28: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast] 2511 | sender_ufda_base = (void __user *)sender_uparent->buffer + fda->parent_offset; | ^ Fixes: 656e01f3ab54 ("binder: read pre-translated fds from sender buffer") Acked-by: Todd Kjos Acked-by: Randy Dunlap # build-tested Acked-by: Christian Brauner Signed-off-by: Arnd Bergmann Link: https://lore.kernel.org/r/20211207122448.1185769-1-arnd@kernel.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Carlos Llamas Signed-off-by: Greg Kroah-Hartman

binder: defer copies of pre-patched txn data

2022-12-08T10:23:01Z

commit 09184ae9b5756cc469db6fd1d1cfdcffbf627c2d upstream. BINDER_TYPE_PTR objects point to memory areas in the source process to be copied into the target buffer as part of a transaction. This implements a scatter- gather model where non-contiguous memory in a source process is "gathered" into a contiguous region in the target buffer. The data can include pointers that must be fixed up to correctly point to the copied data. To avoid making source process pointers visible to the target process, this patch defers the copy until the fixups are known and then copies and fixeups are done together. There is a special case of BINDER_TYPE_FDA which applies the fixup later in the target process context. In this case the user data is skipped (so no untranslated fds become visible to the target). Reviewed-by: Martijn Coenen Signed-off-by: Todd Kjos Link: https://lore.kernel.org/r/20211130185152.437403-5-tkjos@google.com Signed-off-by: Greg Kroah-Hartman [cmllamas: fix trivial merge conflict] Signed-off-by: Carlos Llamas Signed-off-by: Greg Kroah-Hartman

binder: read pre-translated fds from sender buffer

2022-12-08T10:23:01Z

commit 656e01f3ab54afe71bed066996fc2640881e1220 upstream. This patch is to prepare for an up coming patch where we read pre-translated fds from the sender buffer and translate them before copying them to the target. It does not change run time. The patch adds two new parameters to binder_translate_fd_array() to hold the sender buffer and sender buffer parent. These parameters let us call copy_from_user() directly from the sender instead of using binder_alloc_copy_from_buffer() to copy from the target. Also the patch adds some new alignment checks. Previously the alignment checks would have been done in a different place, but this lets us print more useful error messages. Reviewed-by: Martijn Coenen Acked-by: Christian Brauner Signed-off-by: Todd Kjos Link: https://lore.kernel.org/r/20211130185152.437403-4-tkjos@google.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Carlos Llamas Signed-off-by: Greg Kroah-Hartman

binder: avoid potential data leakage when copying txn

2022-12-08T10:23:01Z

commit 6d98eb95b450a75adb4516a1d33652dc78d2b20c upstream. Transactions are copied from the sender to the target first and objects like BINDER_TYPE_PTR and BINDER_TYPE_FDA are then fixed up. This means there is a short period where the sender's version of these objects are visible to the target prior to the fixups. Instead of copying all of the data first, copy data only after any needed fixups have been applied. Fixes: 457b9a6f09f0 ("Staging: android: add binder driver") Reviewed-by: Martijn Coenen Acked-by: Christian Brauner Signed-off-by: Todd Kjos Link: https://lore.kernel.org/r/20211130185152.437403-3-tkjos@google.com Signed-off-by: Greg Kroah-Hartman [cmllamas: fix trivial merge conflict] Signed-off-by: Carlos Llamas Signed-off-by: Greg Kroah-Hartman

binder: fix UAF of alloc->vma in race with munmap()

2022-11-10T16:57:54Z

In commit 720c24192404 ("ANDROID: binder: change down_write to down_read") binder assumed the mmap read lock is sufficient to protect alloc->vma inside binder_update_page_range(). This used to be accurate until commit dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap"), which now downgrades the mmap_lock after detaching the vma from the rbtree in munmap(). Then it proceeds to teardown and free the vma with only the read lock held. This means that accesses to alloc->vma in binder_update_page_range() now will race with vm_area_free() in munmap() and can cause a UAF as shown in the following KASAN trace: ================================================================== BUG: KASAN: use-after-free in vm_insert_page+0x7c/0x1f0 Read of size 8 at addr ffff16204ad00600 by task server/558 CPU: 3 PID: 558 Comm: server Not tainted 5.10.150-00001-gdc8dcf942daa #1 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x2a0 show_stack+0x18/0x2c dump_stack+0xf8/0x164 print_address_description.constprop.0+0x9c/0x538 kasan_report+0x120/0x200 __asan_load8+0xa0/0xc4 vm_insert_page+0x7c/0x1f0 binder_update_page_range+0x278/0x50c binder_alloc_new_buf+0x3f0/0xba0 binder_transaction+0x64c/0x3040 binder_thread_write+0x924/0x2020 binder_ioctl+0x1610/0x2e5c __arm64_sys_ioctl+0xd4/0x120 el0_svc_common.constprop.0+0xac/0x270 do_el0_svc+0x38/0xa0 el0_svc+0x1c/0x2c el0_sync_handler+0xe8/0x114 el0_sync+0x180/0x1c0 Allocated by task 559: kasan_save_stack+0x38/0x6c __kasan_kmalloc.constprop.0+0xe4/0xf0 kasan_slab_alloc+0x18/0x2c kmem_cache_alloc+0x1b0/0x2d0 vm_area_alloc+0x28/0x94 mmap_region+0x378/0x920 do_mmap+0x3f0/0x600 vm_mmap_pgoff+0x150/0x17c ksys_mmap_pgoff+0x284/0x2dc __arm64_sys_mmap+0x84/0xa4 el0_svc_common.constprop.0+0xac/0x270 do_el0_svc+0x38/0xa0 el0_svc+0x1c/0x2c el0_sync_handler+0xe8/0x114 el0_sync+0x180/0x1c0 Freed by task 560: kasan_save_stack+0x38/0x6c kasan_set_track+0x28/0x40 kasan_set_free_info+0x24/0x4c __kasan_slab_free+0x100/0x164 kasan_slab_free+0x14/0x20 kmem_cache_free+0xc4/0x34c vm_area_free+0x1c/0x2c remove_vma+0x7c/0x94 __do_munmap+0x358/0x710 __vm_munmap+0xbc/0x130 __arm64_sys_munmap+0x4c/0x64 el0_svc_common.constprop.0+0xac/0x270 do_el0_svc+0x38/0xa0 el0_svc+0x1c/0x2c el0_sync_handler+0xe8/0x114 el0_sync+0x180/0x1c0 [...] ================================================================== To prevent the race above, revert back to taking the mmap write lock inside binder_update_page_range(). One might expect an increase of mmap lock contention. However, binder already serializes these calls via top level alloc->mutex. Also, there was no performance impact shown when running the binder benchmark tests. Note this patch is specific to stable branches 5.4 and 5.10. Since in newer kernel releases binder no longer caches a pointer to the vma. Instead, it has been refactored to use vma_lookup() which avoids the issue described here. This switch was introduced in commit a43cfc87caaf ("android: binder: stop saving a pointer to the VMA"). Fixes: dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap") Reported-by: Jann Horn Cc: # 5.4.x Cc: Minchan Kim Cc: Yang Shi Cc: Liam Howlett Signed-off-by: Carlos Llamas Signed-off-by: Greg Kroah-Hartman

binder: fix UAF of ref->proc caused by race condition

2022-09-15T10:04:51Z

commit a0e44c64b6061dda7e00b7c458e4523e2331b739 upstream. A transaction of type BINDER_TYPE_WEAK_HANDLE can fail to increment the reference for a node. In this case, the target proc normally releases the failed reference upon close as expected. However, if the target is dying in parallel the call will race with binder_deferred_release(), so the target could have released all of its references by now leaving the cleanup of the new failed reference unhandled. The transaction then ends and the target proc gets released making the ref->proc now a dangling pointer. Later on, ref->node is closed and we attempt to take spin_lock(&ref->proc->inner_lock), which leads to the use-after-free bug reported below. Let's fix this by cleaning up the failed reference on the spot instead of relying on the target to do so. ================================================================== BUG: KASAN: use-after-free in _raw_spin_lock+0xa8/0x150 Write of size 4 at addr ffff5ca207094238 by task kworker/1:0/590 CPU: 1 PID: 590 Comm: kworker/1:0 Not tainted 5.19.0-rc8 #10 Hardware name: linux,dummy-virt (DT) Workqueue: events binder_deferred_func Call trace: dump_backtrace.part.0+0x1d0/0x1e0 show_stack+0x18/0x70 dump_stack_lvl+0x68/0x84 print_report+0x2e4/0x61c kasan_report+0xa4/0x110 kasan_check_range+0xfc/0x1a4 __kasan_check_write+0x3c/0x50 _raw_spin_lock+0xa8/0x150 binder_deferred_func+0x5e0/0x9b0 process_one_work+0x38c/0x5f0 worker_thread+0x9c/0x694 kthread+0x188/0x190 ret_from_fork+0x10/0x20 Acked-by: Christian Brauner (Microsoft) Signed-off-by: Carlos Llamas Cc: stable # 4.14+ Link: https://lore.kernel.org/r/20220801182511.3371447-1-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman

io_uring: disable polling pollfree files

2022-09-05T08:27:47Z

Older kernels lack io_uring POLLFREE handling. As only affected files are signalfd and android binder the safest option would be to disable polling those files via io_uring and hope there are no users. Fixes: 221c5eb233823 ("io_uring: add support for IORING_OP_POLL") Signed-off-by: Pavel Begunkov Signed-off-by: Greg Kroah-Hartman