mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-02 01:06:46 +09:00
1da52815d5
Syzbot reported a couple issues introduced by commit44e602b4e5("binder_alloc: add missing mmap_lock calls when using the VMA"), in which we attempt to acquire the mmap_lock when alloc->vma_vm_mm has not been initialized yet. This can happen if a binder_proc receives a transaction without having previously called mmap() to setup the binder_proc->alloc space in [1]. Also, a similar issue occurs via binder_alloc_print_pages() when we try to dump the debugfs binder stats file in [2]. Sample of syzbot's crash report: ================================================================== KASAN: null-ptr-deref in range [0x0000000000000128-0x000000000000012f] CPU: 0 PID: 3755 Comm: syz-executor229 Not tainted 6.0.0-rc1-next-20220819-syzkaller #0 syz-executor229[3755] cmdline: ./syz-executor2294415195 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 RIP: 0010:__lock_acquire+0xd83/0x56d0 kernel/locking/lockdep.c:4923 [...] Call Trace: <TASK> lock_acquire kernel/locking/lockdep.c:5666 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631 down_read+0x98/0x450 kernel/locking/rwsem.c:1499 mmap_read_lock include/linux/mmap_lock.h:117 [inline] binder_alloc_new_buf_locked drivers/android/binder_alloc.c:405 [inline] binder_alloc_new_buf+0xa5/0x19e0 drivers/android/binder_alloc.c:593 binder_transaction+0x242e/0x9a80 drivers/android/binder.c:3199 binder_thread_write+0x664/0x3220 drivers/android/binder.c:3986 binder_ioctl_write_read drivers/android/binder.c:5036 [inline] binder_ioctl+0x3470/0x6d00 drivers/android/binder.c:5323 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd [...] ================================================================== Fix these issues by setting up alloc->vma_vm_mm pointer during open() and caching directly from current->mm. This guarantees we have a valid reference to take the mmap_lock during scenarios described above. [1] https://syzkaller.appspot.com/bug?extid=f7dc54e5be28950ac459 [2] https://syzkaller.appspot.com/bug?extid=a75ebe0452711c9e56d9 Fixes:44e602b4e5("binder_alloc: add missing mmap_lock calls when using the VMA") Cc: <stable@vger.kernel.org> # v5.15+ Cc: Liam R. Howlett <Liam.Howlett@oracle.com> Reported-by: syzbot+f7dc54e5be28950ac459@syzkaller.appspotmail.com Reported-by: syzbot+a75ebe0452711c9e56d9@syzkaller.appspotmail.com Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com> Acked-by: Todd Kjos <tkjos@google.com> Signed-off-by: Carlos Llamas <cmllamas@google.com> Link: https://lore.kernel.org/r/20220829201254.1814484-2-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.