kernel/linux.git/drivers/android, branch v4.14.181

binder: take read mode of mmap_sem in binder_alloc_free_page()

2020-05-02T15:24:39+00:00

commit 60d4885710836595192c42d3e04b27551d30ec91 upstream. Restore the behavior of locking mmap_sem for reading in binder_alloc_free_page(), as was first done in commit 3013bf62b67a ("binder: reduce mmap_sem write-side lock"). That change was inadvertently reverted by commit 5cec2d2e5839 ("binder: fix race between munmap() and direct reclaim"). In addition, change the name of the label for the error path to accurately reflect that we're taking the lock for reading. Backporting note: This fix is only needed when *both* of the commits mentioned above are applied. That's an unlikely situation since they both landed during the development of v5.1 but only one of them is targeted for stable. Fixes: 5cec2d2e5839 ("binder: fix race between munmap() and direct reclaim") Signed-off-by: Tyler Hicks Acked-by: Todd Kjos Cc: Guenter Roeck Signed-off-by: Greg Kroah-Hartman

binder: Handle start==NULL in binder_update_page_range()

2019-12-17T19:38:57+00:00

commit 2a9edd056ed4fbf9d2e797c3fc06335af35bccc4 upstream. The old loop wouldn't stop when reaching `start` if `start==NULL`, instead continuing backwards to index -1 and crashing. Luckily you need to be highly privileged to map things at NULL, so it's not a big problem. Fix it by adjusting the loop so that the loop variable is always in bounds. This patch is deliberately minimal to simplify backporting, but IMO this function could use a refactor. The jump labels in the second loop body are horrible (the error gotos should be jumping to free_range instead), and both loops would look nicer if they just iterated upwards through indices. And the up_read()+mmput() shouldn't be duplicated like that. Cc: stable@vger.kernel.org Fixes: 457b9a6f09f0 ("Staging: android: add binder driver") Signed-off-by: Jann Horn Acked-by: Christian Brauner Link: https://lore.kernel.org/r/20191018205631.248274-3-jannh@google.com Signed-off-by: Greg Kroah-Hartman

binder: fix possible UAF when freeing buffer

2019-08-04T07:32:01+00:00

commit a370003cc301d4361bae20c9ef615f89bf8d1e8a upstream. There is a race between the binder driver cleaning up a completed transaction via binder_free_transaction() and a user calling binder_ioctl(BC_FREE_BUFFER) to release a buffer. It doesn't matter which is first but they need to be protected against running concurrently which can result in a UAF. Signed-off-by: Todd Kjos Cc: stable Signed-off-by: Greg Kroah-Hartman

binder: prevent transactions to context manager from its own process.

2019-07-31T05:28:57+00:00

commit 49ed96943a8e0c62cc5a9b0a6cfc88be87d1fcec upstream. Currently, a transaction to context manager from its own process is prevented by checking if its binder_proc struct is the same as that of the sender. However, this would not catch cases where the process opens the binder device again and uses the new fd to send a transaction to the context manager. Reported-by: syzbot+8b3c354d33c4ac78bfad@syzkaller.appspotmail.com Signed-off-by: Hridya Valsaraju Acked-by: Todd Kjos Cc: stable Link: https://lore.kernel.org/r/20190715191804.112933-1-hridya@google.com Signed-off-by: Greg Kroah-Hartman

binder: fix memory leak in error path

2019-07-21T07:04:36+00:00

commit 1909a671dbc3606685b1daf8b22a16f65ea7edda upstream. syzkallar found a 32-byte memory leak in a rarely executed error case. The transaction complete work item was not freed if put_user() failed when writing the BR_TRANSACTION_COMPLETE to the user command buffer. Fixed by freeing it before put_user() is called. Reported-by: syzbot+182ce46596c3f2e1eb24@syzkaller.appspotmail.com Signed-off-by: Todd Kjos Cc: stable Signed-off-by: Greg Kroah-Hartman

binder: fix race between munmap() and direct reclaim

2019-06-09T07:18:20+00:00

commit 5cec2d2e5839f9c0fec319c523a911e0a7fd299f upstream. An munmap() on a binder device causes binder_vma_close() to be called which clears the alloc->vma pointer. If direct reclaim causes binder_alloc_free_page() to be called, there is a race where alloc->vma is read into a local vma pointer and then used later after the mm->mmap_sem is acquired. This can result in calling zap_page_range() with an invalid vma which manifests as a use-after-free in zap_page_range(). The fix is to check alloc->vma after acquiring the mmap_sem (which we were acquiring anyway) and skip zap_page_range() if it has changed to NULL. Cc: Ben Hutchings Signed-off-by: Todd Kjos Reviewed-by: Joel Fernandes (Google) Cc: stable # 4.14 Signed-off-by: Greg Kroah-Hartman

Revert "binder: fix handling of misaligned binder object"

2019-06-09T07:18:20+00:00

This reverts commit 33c6b9ca70a8b066a613e2a3d0331ae8f82aa31a. The commit message is for a different patch. Reverting and then adding the same patch back with the correct commit message. Reported-by: Ben Hutchings Cc: stable # 4.14 Signed-off-by: Todd Kjos Signed-off-by: Greg Kroah-Hartman

binder: fix handling of misaligned binder object

2019-05-02T07:40:31+00:00

commit 26528be6720bb40bc8844e97ee73a37e530e9c5e upstream. Fixes crash found by syzbot: kernel BUG at drivers/android/binder_alloc.c:LINE! (2) Reported-and-tested-by: syzbot+55de1eb4975dec156d8f@syzkaller.appspotmail.com Signed-off-by: Todd Kjos Reviewed-by: Joel Fernandes (Google) Cc: stable # 5.0, 4.19, 4.14 Signed-off-by: Greg Kroah-Hartman

binder: fix race that allows malicious free of live buffer

2018-12-05T18:41:26+00:00

commit 7bada55ab50697861eee6bb7d60b41e68a961a9c upstream. Malicious code can attempt to free buffers using the BC_FREE_BUFFER ioctl to binder. There are protections against a user freeing a buffer while in use by the kernel, however there was a window where BC_FREE_BUFFER could be used to free a recently allocated buffer that was not completely initialized. This resulted in a use-after-free detected by KASAN with a malicious test program. This window is closed by setting the buffer's allow_user_free attribute to 0 when the buffer is allocated or when the user has previously freed it instead of waiting for the caller to set it. The problem was that when the struct buffer was recycled, allow_user_free was stale and set to 1 allowing a free to go through. Signed-off-by: Todd Kjos Acked-by: Arve Hjønnevåg Cc: stable # 4.14 Signed-off-by: Greg Kroah-Hartman

android: binder: fix the race mmap and alloc_new_buf_locked

2018-09-19T20:43:35+00:00

commit da1b9564e85b1d7baf66cbfabcab27e183a1db63 upstream. There is RaceFuzzer report like below because we have no lock to close below the race between binder_mmap and binder_alloc_new_buf_locked. To close the race, let's use memory barrier so that if someone see alloc->vma is not NULL, alloc->vma_vm_mm should be never NULL. (I didn't add stable mark intentionallybecause standard android userspace libraries that interact with binder (libbinder & libhwbinder) prevent the mmap/ioctl race. - from Todd) " Thread interleaving: CPU0 (binder_alloc_mmap_handler) CPU1 (binder_alloc_new_buf_locked) ===== ===== // drivers/android/binder_alloc.c // #L718 (v4.18-rc3) alloc->vma = vma; // drivers/android/binder_alloc.c // #L346 (v4.18-rc3) if (alloc->vma == NULL) { ... // alloc->vma is not NULL at this point return ERR_PTR(-ESRCH); } ... // #L438 binder_update_page_range(alloc, 0, (void *)PAGE_ALIGN((uintptr_t)buffer->data), end_page_addr); // In binder_update_page_range() #L218 // But still alloc->vma_vm_mm is NULL here if (need_mm && mmget_not_zero(alloc->vma_vm_mm)) alloc->vma_vm_mm = vma->vm_mm; Crash Log: ================================================================== BUG: KASAN: null-ptr-deref in __atomic_add_unless include/asm-generic/atomic-instrumented.h:89 [inline] BUG: KASAN: null-ptr-deref in atomic_add_unless include/linux/atomic.h:533 [inline] BUG: KASAN: null-ptr-deref in mmget_not_zero include/linux/sched/mm.h:75 [inline] BUG: KASAN: null-ptr-deref in binder_update_page_range+0xece/0x18e0 drivers/android/binder_alloc.c:218 Write of size 4 at addr 0000000000000058 by task syz-executor0/11184 CPU: 1 PID: 11184 Comm: syz-executor0 Not tainted 4.18.0-rc3 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x16e/0x22c lib/dump_stack.c:113 kasan_report_error mm/kasan/report.c:352 [inline] kasan_report+0x163/0x380 mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x140/0x1a0 mm/kasan/kasan.c:267 kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278 __atomic_add_unless include/asm-generic/atomic-instrumented.h:89 [inline] atomic_add_unless include/linux/atomic.h:533 [inline] mmget_not_zero include/linux/sched/mm.h:75 [inline] binder_update_page_range+0xece/0x18e0 drivers/android/binder_alloc.c:218 binder_alloc_new_buf_locked drivers/android/binder_alloc.c:443 [inline] binder_alloc_new_buf+0x467/0xc30 drivers/android/binder_alloc.c:513 binder_transaction+0x125b/0x4fb0 drivers/android/binder.c:2957 binder_thread_write+0xc08/0x2770 drivers/android/binder.c:3528 binder_ioctl_write_read.isra.39+0x24f/0x8e0 drivers/android/binder.c:4456 binder_ioctl+0xa86/0xf34 drivers/android/binder.c:4596 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x154/0xd40 fs/ioctl.c:686 ksys_ioctl+0x94/0xb0 fs/ioctl.c:701 __do_sys_ioctl fs/ioctl.c:708 [inline] __se_sys_ioctl fs/ioctl.c:706 [inline] __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:706 do_syscall_64+0x167/0x4b0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe " Signed-off-by: Todd Kjos Signed-off-by: Minchan Kim Reviewed-by: Martijn Coenen Cc: stable Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman