linux/drivers/android, branch v5.4

binder: Don't modify VMA bounds in ->mmap handler

2019-10-17T12:58:44Z

binder_mmap() tries to prevent the creation of overly big binder mappings by silently truncating the size of the VMA to 4MiB. However, this violates the API contract of mmap(). If userspace attempts to create a large binder VMA, and later attempts to unmap that VMA, it will call munmap() on a range beyond the end of the VMA, which may have been allocated to another VMA in the meantime. This can lead to userspace memory corruption. The following sequence of calls leads to a segfault without this commit: int main(void) { int binder_fd = open("/dev/binder", O_RDWR); if (binder_fd == -1) err(1, "open binder"); void *binder_mapping = mmap(NULL, 0x800000UL, PROT_READ, MAP_SHARED, binder_fd, 0); if (binder_mapping == MAP_FAILED) err(1, "mmap binder"); void *data_mapping = mmap(NULL, 0x400000UL, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); if (data_mapping == MAP_FAILED) err(1, "mmap data"); munmap(binder_mapping, 0x800000UL); *(char*)data_mapping = 1; return 0; } Cc: stable@vger.kernel.org Signed-off-by: Jann Horn Acked-by: Todd Kjos Acked-by: Christian Brauner Link: https://lore.kernel.org/r/20191016150119.154756-1-jannh@google.com Signed-off-by: Greg Kroah-Hartman

binder: Fix comment headers on binder_alloc_prepare_to_free()

2019-10-10T12:39:23Z

binder_alloc_buffer_lookup() doesn't exist and is named "binder_alloc_prepare_to_free()". Correct the code comments to reflect this. Signed-off-by: Joel Fernandes (Google) Reviewed-by: Christian Brauner Link: https://lore.kernel.org/r/20190930201250.139554-1-joel@joelfernandes.org Signed-off-by: Greg Kroah-Hartman

binder: prevent UAF read in print_binder_transaction_log_entry()

2019-10-10T12:39:22Z

When a binder transaction is initiated on a binder device coming from a binderfs instance, a pointer to the name of the binder device is stashed in the binder_transaction_log_entry's context_name member. Later on it is used to print the name in print_binder_transaction_log_entry(). By the time print_binder_transaction_log_entry() accesses context_name binderfs_evict_inode() might have already freed the associated memory thereby causing a UAF. Do the simple thing and prevent this by copying the name of the binder device instead of stashing a pointer to it. Reported-by: Jann Horn Fixes: 03e2e07e3814 ("binder: Make transaction_log available in binderfs") Link: https://lore.kernel.org/r/CAG48ez14Q0-F8LqsvcNbyR2o6gPW8SHXsm4u5jmD9MpsteM2Tw@mail.gmail.com Signed-off-by: Christian Brauner Reviewed-by: Joel Fernandes (Google) Acked-by: Todd Kjos Reviewed-by: Hridya Valsaraju Link: https://lore.kernel.org/r/20191008130159.10161-1-christian.brauner@ubuntu.com Signed-off-by: Greg Kroah-Hartman

binder: Add binder_proc logging to binderfs

2019-09-04T11:31:26Z

Currently /sys/kernel/debug/binder/proc contains the debug data for every binder_proc instance. This patch makes this information also available in a binderfs instance mounted with a mount option "stats=global" in addition to debugfs. The patch does not affect the presence of the file in debugfs. If a binderfs instance is mounted at path /dev/binderfs, this file would be present at /dev/binderfs/binder_logs/proc. This change provides an alternate way to access this file when debugfs is not mounted. Acked-by: Christian Brauner Signed-off-by: Hridya Valsaraju Link: https://lore.kernel.org/r/20190903161655.107408-5-hridya@google.com Signed-off-by: Greg Kroah-Hartman

binder: Make transaction_log available in binderfs

2019-09-04T11:31:22Z

Currently, the binder transaction log files 'transaction_log' and 'failed_transaction_log' live in debugfs at the following locations: /sys/kernel/debug/binder/failed_transaction_log /sys/kernel/debug/binder/transaction_log This patch makes these files also available in a binderfs instance mounted with the mount option "stats=global". It does not affect the presence of these files in debugfs. If a binderfs instance is mounted at path /dev/binderfs, the location of these files will be as follows: /dev/binderfs/binder_logs/failed_transaction_log /dev/binderfs/binder_logs/transaction_log This change provides an alternate option to access these files when debugfs is not mounted. Acked-by: Christian Brauner Signed-off-by: Hridya Valsaraju Link: https://lore.kernel.org/r/20190903161655.107408-4-hridya@google.com Signed-off-by: Greg Kroah-Hartman

binder: Add stats, state and transactions files

2019-09-04T11:31:18Z

The following binder stat files currently live in debugfs. /sys/kernel/debug/binder/state /sys/kernel/debug/binder/stats /sys/kernel/debug/binder/transactions This patch makes these files available in a binderfs instance mounted with the mount option 'stats=global'. For example, if a binderfs instance is mounted at path /dev/binderfs, the above files will be available at the following locations: /dev/binderfs/binder_logs/state /dev/binderfs/binder_logs/stats /dev/binderfs/binder_logs/transactions This provides a way to access them even when debugfs is not mounted. Acked-by: Christian Brauner Signed-off-by: Hridya Valsaraju Acked-by: Christian Brauner Link: https://lore.kernel.org/r/20190903161655.107408-3-hridya@google.com Signed-off-by: Greg Kroah-Hartman

binder: add a mount option to show global stats

2019-09-04T11:31:13Z

Currently, all binder state and statistics live in debugfs. We need this information even when debugfs is not mounted. This patch adds the mount option 'stats' to enable a binderfs instance to have binder debug information present in the same. 'stats=global' will enable the global binder statistics. In the future, 'stats=local' will enable binder statistics local to the binderfs instance. The two modes 'global' and 'local' will be mutually exclusive. 'stats=global' option is only available for a binderfs instance mounted in the initial user namespace. An attempt to use the option to mount a binderfs instance in another user namespace will return an EPERM error. Signed-off-by: Hridya Valsaraju Acked-by: Christian Brauner Link: https://lore.kernel.org/r/20190903161655.107408-2-hridya@google.com Signed-off-by: Greg Kroah-Hartman

binder: Add default binder devices through binderfs when configured

2019-09-04T11:17:35Z

Currently, since each binderfs instance needs its own private binder devices, every time a binderfs instance is mounted, all the default binder devices need to be created via the BINDER_CTL_ADD IOCTL. This patch aims to add a solution to automatically create the default binder devices for each binderfs instance that gets mounted. To achieve this goal, when CONFIG_ANDROID_BINDERFS is set, the default binder devices specified by CONFIG_ANDROID_BINDER_DEVICES are created in each binderfs instance instead of global devices being created by the binder driver. Co-developed-by: Christian Brauner Signed-off-by: Christian Brauner Signed-off-by: Hridya Valsaraju Reviewed-by: Joel Fernandes (Google) Link: https://lore.kernel.org/r/20190808222727.132744-2-hridya@google.com Link: https://lore.kernel.org/r/20190904110704.8606-2-christian.brauner@ubuntu.com Signed-off-by: Greg Kroah-Hartman

binder: Validate the default binderfs device names.

2019-09-04T11:17:35Z

Length of a binderfs device name cannot exceed BINDERFS_MAX_NAME. This patch adds a check in binderfs_init() to ensure the same for the default binder devices that will be created in every binderfs instance. Co-developed-by: Christian Brauner Signed-off-by: Christian Brauner Signed-off-by: Hridya Valsaraju Reviewed-by: Joel Fernandes (Google) Link: https://lore.kernel.org/r/20190808222727.132744-3-hridya@google.com Link: https://lore.kernel.org/r/20190904110704.8606-3-christian.brauner@ubuntu.com Signed-off-by: Greg Kroah-Hartman

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

2019-07-24T09:02:28Z

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