Re: [syzbot] [bluetooth?] KASAN: slab-out-of-bounds Read in l2cap_sock_setsockopt

[Hillf Danton]

On Thu, 04 Apr 2024 23:55:25 -0700
> syzbot found the following issue on:
> 
> HEAD commit:    707081b61156 Merge branch 'for-next/core', remote-tracking..
> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15c6098d180000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git  fe46a7dd189e

--- x/net/bluetooth/l2cap_sock.c
+++ y/net/bluetooth/l2cap_sock.c
@@ -960,7 +960,7 @@ static int l2cap_sock_setsockopt(struct
 			break;
 		}
 
-		if (copy_from_sockptr(&opt, optval, sizeof(u32))) {
+		if (optlen < sizeof(u32) || copy_from_sockptr(&opt, optval, sizeof(u32))) {
 			err = -EFAULT;
 			break;
 		}
--