linux/drivers/android/binder.c, branch v4.20

binder: fix race that allows malicious free of live buffer

2018-11-26T19:01:47Z

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

binder: make symbol 'binder_free_buf' static

2018-10-02T22:53:53Z

Fixes the following sparse warning: drivers/android/binder.c:3312:1: warning: symbol 'binder_free_buf' was not declared. Should it be static? Signed-off-by: Wei Yongjun Signed-off-by: Greg Kroah-Hartman

binder: Add BINDER_GET_NODE_INFO_FOR_REF ioctl.

2018-09-14T13:22:48Z

This allows the context manager to retrieve information about nodes that it holds a reference to, such as the current number of references to those nodes. Such information can for example be used to determine whether the servicemanager is the only process holding a reference to a node. This information can then be passed on to the process holding the node, which can in turn decide whether it wants to shut down to reduce resource usage. Signed-off-by: Martijn Coenen Signed-off-by: Greg Kroah-Hartman

android: binder: use kstrdup instead of open-coding it

2018-09-14T13:22:36Z

Signed-off-by: Rasmus Villemoes Signed-off-by: Greg Kroah-Hartman

binder: use standard functions to allocate fds

2018-09-14T13:22:36Z

Binder uses internal fs interfaces to allocate and install fds: __alloc_fd __fd_install __close_fd get_files_struct put_files_struct These were used to support the passing of fds between processes as part of a transaction. The actual allocation and installation of the fds in the target process was handled by the sending process so the standard functions, alloc_fd() and fd_install() which assume task==current couldn't be used. This patch refactors this mechanism so that the fds are allocated and installed by the target process allowing the standard functions to be used. The sender now creates a list of fd fixups that contains the struct *file and the address to fixup with the new fd once it is allocated. This list is processed by the target process when the transaction is dequeued. A new error case is introduced by this change. If an async transaction with file descriptors cannot allocate new fds in the target (probably due to out of file descriptors), the transaction is discarded with a log message. In the old implementation this would have been detected in the sender context and failed prior to sending. Signed-off-by: Todd Kjos Signed-off-by: Greg Kroah-Hartman

android: binder: no outgoing transaction when thread todo has transaction

2018-09-14T13:22:36Z

When a process dies, failed reply is sent to the sender of any transaction queued on a dead thread's todo list. The sender asserts that the received failed reply corresponds to the head of the transaction stack. This assert can fail if the dead thread is allowed to send outgoing transactions when there is already a transaction on its todo list, because this new transaction can end up on the transaction stack of the original sender. The following steps illustrate how this assertion can fail. 1. Thread1 sends txn19 to Thread2 (T1->transaction_stack=txn19, T2->todo+=txn19) 2. Without processing todo list, Thread2 sends txn20 to Thread1 (T1->todo+=txn20, T2->transaction_stack=txn20) 3. T1 processes txn20 on its todo list (T1->transaction_stack=txn20->txn19, T1->todo=) 4. T2 dies, T2->todo cleanup attempts to send failed reply for txn19, but T1->transaction_stack points to txn20 -- assertion failes Step 2. is the incorrect behavior. When there is a transaction on a thread's todo list, this thread should not be able to send any outgoing synchronous transactions. Only the head of the todo list needs to be checked because only threads that are waiting for proc work can directly receive work from another thread, and no work is allowed to be queued on such a thread without waking up the thread. This patch also enforces that a thread is not waiting for proc work when a work is directly enqueued to its todo list. Acked-by: Arve Hjønnevåg Signed-off-by: Sherry Yang Reviewed-by: Martijn Coenen Signed-off-by: Greg Kroah-Hartman

android: binder: Rate-limit debug and userspace triggered err msgs

2018-08-08T09:05:47Z

Use rate-limited debug messages where userspace can trigger excessive log spams. Acked-by: Arve Hjønnevåg Signed-off-by: Sherry Yang Signed-off-by: Greg Kroah-Hartman

android: binder: Include asm/cacheflush.h after linux/ include files

2018-07-24T12:23:00Z

If asm/cacheflush.h is included first, the following build warnings are seen with sparc32 builds. In file included from arch/sparc/include/asm/cacheflush.h:11:0, from drivers/android/binder.c:54: arch/sparc/include/asm/cacheflush_32.h:40:37: warning: 'struct page' declared inside parameter list will not be visible outside of this definition or declaration Moving the asm/ include after linux/ includes solves the problem. Suggested-by: Linus Torvalds Signed-off-by: Guenter Roeck Signed-off-by: Greg Kroah-Hartman

android: binder: Change return type to vm_fault_t

2018-05-14T14:06:48Z

Use new return type vm_fault_t for fault handler in struct vm_operations_struct. For now, this is just documenting that the function returns a VM_FAULT value rather than an errno. Once all instances are converted, vm_fault_t will become a distinct type. Reference id -> 1c8f422059ae ("mm: change return type to vm_fault_t") Signed-off-by: Souptick Joarder Signed-off-by: Greg Kroah-Hartman

ANDROID: binder: change down_write to down_read

2018-05-14T14:06:48Z

binder_update_page_range needs down_write of mmap_sem because vm_insert_page need to change vma->vm_flags to VM_MIXEDMAP unless it is set. However, when I profile binder working, it seems every binder buffers should be mapped in advance by binder_mmap. It means we could set VM_MIXEDMAP in binder_mmap time which is already hold a mmap_sem as down_write so binder_update_page_range doesn't need to hold a mmap_sem as down_write. Please use proper API down_read. It would help mmap_sem contention problem as well as fixing down_write abuse. Ganesh Mahendran tested app launching and binder throughput test and he said he couldn't find any problem and I did binder latency test per Greg KH request(Thanks Martijn to teach me how I can do) I cannot find any problem, too. Cc: Ganesh Mahendran Cc: Joe Perches Cc: Arve Hjønnevåg Cc: Todd Kjos Reviewed-by: Martijn Coenen Signed-off-by: Minchan Kim Reviewed-by: Joel Fernandes (Google) Signed-off-by: Greg Kroah-Hartman