On Wed, 2024-04-03 at 14:54 +0800, Edward Adam Davis wrote:
> [Syzbot reported]
> BUG: KASAN: slab-out-of-bounds in instrument_copy_from_user_before include/linux/instrumented.h:129 [inline]
> BUG: KASAN: slab-out-of-bounds in _copy_from_user+0x7b/0xe0 lib/usercopy.c:22
> Write of size 48 at addr ffff88802b8cbc88 by task syz-executor333/5090
>
> CPU: 0 PID: 5090 Comm: syz-executor333 Not tainted 6.9.0-rc2-next-20240402-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:88 [inline]
> dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
> print_address_description mm/kasan/report.c:377 [inline]
> print_report+0x169/0x550 mm/kasan/report.c:488
> kasan_report+0x143/0x180 mm/kasan/report.c:601
> kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
> instrument_copy_from_user_before include/linux/instrumented.h:129 [inline]
> _copy_from_user+0x7b/0xe0 lib/usercopy.c:22
> copy_from_user include/linux/uaccess.h:183 [inline]
> handle_to_path fs/fhandle.c:203 [inline]
> do_handle_open+0x204/0x660 fs/fhandle.c:226
> do_syscall_64+0xfb/0x240
> entry_SYSCALL_64_after_hwframe+0x72/0x7a
> [Fix]
> When copying data to f_handle, the length of the copied data should not include
> the length of "struct file_handle".
>
> Reported-by: syzbot+4139435cb1b34cf759c2@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Edward Adam Davis <eadavis@xxxxxx>
> ---
> fs/fhandle.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/fhandle.c b/fs/fhandle.c
> index 53ed54711cd2..8a7f86c2139a 100644
> --- a/fs/fhandle.c
> +++ b/fs/fhandle.c
> @@ -202,7 +202,7 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
> *handle = f_handle;
> if (copy_from_user(&handle->f_handle,
> &ufh->f_handle,
> - struct_size(ufh, f_handle, f_handle.handle_bytes))) {
> + f_handle.handle_bytes)) {
> retval = -EFAULT;
> goto out_handle;
> }
cc'ing Gustavo, since it looks like his patch in -next is what broke
this.
--
Jeff Layton <jlayton@xxxxxxxxxx>
