tree e2623d724b9a0b2e7a8fbcd7483f51c7892cc351
parent 75613ba0ee43c74bb35bb8f80961e8e0ea496f9f
author Johannes Thumshirn <johannes.thumshirn@wdc.com> 1713343547 +0200
committer Vegard Nossum <vegard.nossum@oracle.com> 1717160247 +0000

btrfs: fix information leak in btrfs_ioctl_logical_to_ino()

commit 2f7ef5bb4a2f3e481ef05fab946edb97c84f67cf upstream.

Syzbot reported the following information leak for in
btrfs_ioctl_logical_to_ino():

  BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline]
  BUG: KMSAN: kernel-infoleak in _copy_to_user+0xbc/0x110 lib/usercopy.c:40
   instrument_copy_to_user include/linux/instrumented.h:114 [inline]
   _copy_to_user+0xbc/0x110 lib/usercopy.c:40
   copy_to_user include/linux/uaccess.h:191 [inline]
   btrfs_ioctl_logical_to_ino+0x440/0x750 fs/btrfs/ioctl.c:3499
   btrfs_ioctl+0x714/0x1260
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:904 [inline]
   __se_sys_ioctl+0x261/0x450 fs/ioctl.c:890
   __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:890
   x64_sys_call+0x1883/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:17
   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
   do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

  Uninit was created at:
   __kmalloc_large_node+0x231/0x370 mm/slub.c:3921
   __do_kmalloc_node mm/slub.c:3954 [inline]
   __kmalloc_node+0xb07/0x1060 mm/slub.c:3973
   kmalloc_node include/linux/slab.h:648 [inline]
   kvmalloc_node+0xc0/0x2d0 mm/util.c:634
   kvmalloc include/linux/slab.h:766 [inline]
   init_data_container+0x49/0x1e0 fs/btrfs/backref.c:2779
   btrfs_ioctl_logical_to_ino+0x17c/0x750 fs/btrfs/ioctl.c:3480
   btrfs_ioctl+0x714/0x1260
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:904 [inline]
   __se_sys_ioctl+0x261/0x450 fs/ioctl.c:890
   __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:890
   x64_sys_call+0x1883/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:17
   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
   do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

  Bytes 40-65535 of 65536 are uninitialized
  Memory access of size 65536 starts at ffff888045a40000

This happens, because we're copying a 'struct btrfs_data_container' back
to user-space. This btrfs_data_container is allocated in
'init_data_container()' via kvmalloc(), which does not zero-fill the
memory.

Fix this by using kvzalloc() which zeroes out the memory on allocation.

CC: stable@vger.kernel.org # 4.14+
Reported-by:  <syzbot+510a1abbb8116eeb341d@syzkaller.appspotmail.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Johannes Thumshirn <Johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 689efe22e9b5b7d9d523119a9a5c3c17107a0772)
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>