diff options
| -rw-r--r-- | drivers/android/binder.c | 63 | ||||
| -rw-r--r-- | fs/file.c | 29 | ||||
| -rw-r--r-- | include/linux/fdtable.h | 1 |
3 files changed, 91 insertions, 2 deletions
diff --git a/drivers/android/binder.c b/drivers/android/binder.c index d653e8a474fc..210940bd0457 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -72,6 +72,7 @@ #include <linux/spinlock.h> #include <linux/ratelimit.h> #include <linux/syscalls.h> +#include <linux/task_work.h> #include <uapi/linux/android/binder.h> @@ -2170,6 +2171,64 @@ static bool binder_validate_fixup(struct binder_buffer *b, return (fixup_offset >= last_min_offset); } +/** + * struct binder_task_work_cb - for deferred close + * + * @twork: callback_head for task work + * @fd: fd to close + * + * Structure to pass task work to be handled after + * returning from binder_ioctl() via task_work_add(). + */ +struct binder_task_work_cb { + struct callback_head twork; + struct file *file; +}; + +/** + * binder_do_fd_close() - close list of file descriptors + * @twork: callback head for task work + * + * It is not safe to call ksys_close() during the binder_ioctl() + * function if there is a chance that binder's own file descriptor + * might be closed. This is to meet the requirements for using + * fdget() (see comments for __fget_light()). Therefore use + * task_work_add() to schedule the close operation once we have + * returned from binder_ioctl(). This function is a callback + * for that mechanism and does the actual ksys_close() on the + * given file descriptor. + */ +static void binder_do_fd_close(struct callback_head *twork) +{ + struct binder_task_work_cb *twcb = container_of(twork, + struct binder_task_work_cb, twork); + + fput(twcb->file); + kfree(twcb); +} + +/** + * binder_deferred_fd_close() - schedule a close for the given file-descriptor + * @fd: file-descriptor to close + * + * See comments in binder_do_fd_close(). This function is used to schedule + * a file-descriptor to be closed after returning from binder_ioctl(). + */ +static void binder_deferred_fd_close(int fd) +{ + struct binder_task_work_cb *twcb; + + twcb = kzalloc(sizeof(*twcb), GFP_KERNEL); + if (!twcb) + return; + init_task_work(&twcb->twork, binder_do_fd_close); + __close_fd_get_file(fd, &twcb->file); + if (twcb->file) + task_work_add(current, &twcb->twork, true); + else + kfree(twcb); +} + static void binder_transaction_buffer_release(struct binder_proc *proc, struct binder_buffer *buffer, binder_size_t *failed_at) @@ -2309,7 +2368,7 @@ static void binder_transaction_buffer_release(struct binder_proc *proc, } fd_array = (u32 *)(parent_buffer + (uintptr_t)fda->parent_offset); for (fd_index = 0; fd_index < fda->num_fds; fd_index++) - ksys_close(fd_array[fd_index]); + binder_deferred_fd_close(fd_array[fd_index]); } break; default: pr_err("transaction release %d bad object type %x\n", @@ -3928,7 +3987,7 @@ static int binder_apply_fd_fixups(struct binder_transaction *t) } else if (ret) { u32 *fdp = (u32 *)(t->buffer->data + fixup->offset); - ksys_close(*fdp); + binder_deferred_fd_close(*fdp); } list_del(&fixup->fixup_entry); kfree(fixup); diff --git a/fs/file.c b/fs/file.c index 7ffd6e9d103d..8d059d8973e9 100644 --- a/fs/file.c +++ b/fs/file.c @@ -640,6 +640,35 @@ out_unlock: } EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ +/* + * variant of __close_fd that gets a ref on the file for later fput + */ +int __close_fd_get_file(unsigned int fd, struct file **res) +{ + struct files_struct *files = current->files; + struct file *file; + struct fdtable *fdt; + + spin_lock(&files->file_lock); + fdt = files_fdtable(files); + if (fd >= fdt->max_fds) + goto out_unlock; + file = fdt->fd[fd]; + if (!file) + goto out_unlock; + rcu_assign_pointer(fdt->fd[fd], NULL); + __put_unused_fd(files, fd); + spin_unlock(&files->file_lock); + get_file(file); + *res = file; + return filp_close(file, files); + +out_unlock: + spin_unlock(&files->file_lock); + *res = NULL; + return -ENOENT; +} + void do_close_on_exec(struct files_struct *files) { unsigned i; diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h index 41615f38bcff..f07c55ea0c22 100644 --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -121,6 +121,7 @@ extern void __fd_install(struct files_struct *files, unsigned int fd, struct file *file); extern int __close_fd(struct files_struct *files, unsigned int fd); +extern int __close_fd_get_file(unsigned int fd, struct file **res); extern struct kmem_cache *files_cachep; |