5.4-stable review patch. If anyone has any objections, please let me know.
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From: Andrej Shadura andrew.shadura@collabora.co.uk
commit 5fe6caa62b07fd39cd6a28acc8f92ba2955e11a6 upstream.
Commit 9bf4e919ccad 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: Aleksei Vetrov vvvvvv@google.com Improves: 9bf4e919ccad ("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: Andrej Shadura andrew.shadura@collabora.co.uk Reviewed-by: Nathan Chancellor nathan@kernel.org Signed-off-by: Luiz Augusto von Dentz luiz.von.dentz@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/bluetooth/rfcomm/sock.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
--- a/net/bluetooth/rfcomm/sock.c +++ b/net/bluetooth/rfcomm/sock.c @@ -736,7 +736,8 @@ static int rfcomm_sock_getsockopt_old(st 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); @@ -790,7 +791,7 @@ static int rfcomm_sock_getsockopt_old(st 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;
@@ -809,7 +810,8 @@ static int rfcomm_sock_getsockopt(struct { struct sock *sk = sock->sk; struct bt_security sec; - int len, err = 0; + int err = 0; + size_t len;
BT_DBG("sk %p", sk);
@@ -834,7 +836,7 @@ static int rfcomm_sock_getsockopt(struct 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;