On 03/04/24 02:48, Jeff Layton wrote:
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.
Oh, sorry about that folks. That looks pretty much like a copy/paste error. The fix is correct. Thanks, Edward! -- Gustavo
