i2c/designware: Fix an initialization issue

JIRA: https://issues.redhat.com/browse/RHEL-106627
CVE: CVE-2025-38380

commit 3d30048
Author: Michael J. Ruhl <michael.j.ruhl@intel.com>
Date:   Fri Jun 27 10:35:11 2025 -0400

    i2c/designware: Fix an initialization issue

    The i2c_dw_xfer_init() function requires msgs and msg_write_idx from the
    dev context to be initialized.

    amd_i2c_dw_xfer_quirk() inits msgs and msgs_num, but not msg_write_idx.

    This could allow an out of bounds access (of msgs).

    Initialize msg_write_idx before calling i2c_dw_xfer_init().

    Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
    Fixes: 17631e8 ("i2c: designware: Add driver support for AMD NAVI GPU")
    Cc: <stable@vger.kernel.org> # v5.13+
    Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
    Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
    Link: https://lore.kernel.org/r/20250627143511.489570-1-michael.j.ruhl@intel.com

Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>

Author: CKI Backport Bot

drivers/i2c/busses/i2c-designware-master.c

@@ -345,6 +345,7 @@ static int amd_i2c_dw_xfer_quirk(struct i2c_adapter *adap, struct i2c_msg *msgs,
 
 	dev->msgs = msgs;
 	dev->msgs_num = num_msgs;
+	dev->msg_write_idx = 0;
 	i2c_dw_xfer_init(dev);
 
 	/* Initiate messages read/write transaction */