Commit 5fe6caa6 authored by Andrej Shadura's avatar Andrej Shadura Committed by Luiz Augusto von Dentz
Browse files

Bluetooth: Fix type of len in rfcomm_sock_getsockopt{,_old}() 



Commit 9bf4e919 worked around an issue introduced after an innocuous
optimisation change in LLVM main:

> len is defined as an 'int' because it is assigned from
> '__user int *optlen'. However, it is clamped against the result of
> sizeof(), which has a type of 'size_t' ('unsigned long' for 64-bit
> platforms). This is done with min_t() because min() requires compatible
> types, which results in both len and the result of sizeof() being casted
> to 'unsigned int', meaning len changes signs and the result of sizeof()
> is truncated. From there, len is passed to copy_to_user(), which has a
> third parameter type of 'unsigned long', so it is widened and changes
> signs again. This excessive casting in combination with the KCSAN
> instrumentation causes LLVM to fail to eliminate the __bad_copy_from()
> call, failing the build.

The same issue occurs in rfcomm in functions rfcomm_sock_getsockopt and
rfcomm_sock_getsockopt_old.

Change the type of len to size_t in both rfcomm_sock_getsockopt and
rfcomm_sock_getsockopt_old and replace min_t() with min().

Cc: stable@vger.kernel.org
Co-authored-by: default avatarAleksei Vetrov <vvvvvv@google.com>
Improves: 9bf4e919 ("Bluetooth: Fix type of len in {l2cap,sco}_sock_getsockopt_old()")
Link: https://github.com/ClangBuiltLinux/linux/issues/2007
Link: https://github.com/llvm/llvm-project/issues/85647


Signed-off-by: default avatarAndrej Shadura <andrew.shadura@collabora.co.uk>
Reviewed-by: default avatarNathan Chancellor <nathan@kernel.org>
Signed-off-by: default avatarLuiz Augusto von Dentz <luiz.von.dentz@intel.com>
parent 510e8380

net/bluetooth/rfcomm/sock.c

+6 −4
Original line number Diff line number Diff line
@@ -729,7 +729,8 @@ static int rfcomm_sock_getsockopt_old(struct socket *sock, int optname, char __u 
	struct sock *l2cap_sk;

	struct l2cap_conn *conn;

	struct rfcomm_conninfo cinfo;

	int len, err = 0;

	int err = 0;

	size_t len;

	u32 opt;



	BT_DBG("sk %p", sk);
@@ -783,7 +784,7 @@ static int rfcomm_sock_getsockopt_old(struct socket *sock, int optname, char __u 
		cinfo.hci_handle = conn->hcon->handle;

		memcpy(cinfo.dev_class, conn->hcon->dev_class, 3);



		len = min_t(unsigned int, len, sizeof(cinfo));

		len = min(len, sizeof(cinfo));

		if (copy_to_user(optval, (char *) &cinfo, len))

			err = -EFAULT;
@@ -802,7 +803,8 @@ static int rfcomm_sock_getsockopt(struct socket *sock, int level, int optname, c 
{

	struct sock *sk = sock->sk;

	struct bt_security sec;

	int len, err = 0;

	int err = 0;

	size_t len;



	BT_DBG("sk %p", sk);
@@ -827,7 +829,7 @@ static int rfcomm_sock_getsockopt(struct socket *sock, int level, int optname, c 
		sec.level = rfcomm_pi(sk)->sec_level;

		sec.key_size = 0;



		len = min_t(unsigned int, len, sizeof(sec));

		len = min(len, sizeof(sec));

		if (copy_to_user(optval, (char *) &sec, len))

			err = -EFAULT;