[Bug 282237] bhyve: usb_mouse.c segfaults due to incomplete NULL checking

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=282237

--- Comment #1 from commit-hook@FreeBSD.org ---
A commit in branch main references this bug:

URL:
https://cgit.FreeBSD.org/src/commit/?id=7631790422464de1aec309018e2c444defe5f629

commit 7631790422464de1aec309018e2c444defe5f629
Author:     Jack Bendtsen <jackdbendtsen@gmail.com>
AuthorDate: 2025-06-19 07:40:31 +0000
Commit:     Warner Losh <imp@FreeBSD.org>
CommitDate: 2026-01-09 20:17:13 +0000

    Fix NULL deref segfault in bhyve's usb_mouse.c

    Some of the cases inside umouse_request() (usr.sbin/bhyve/usb_mouse.c)
    use the data component of an event, while only partially checking if
    it's NULL. 'data' has a NULL check, but then 'data' is immediately
    deferenced anyway after the check regardless of if it's NULL or not.

    For example:
            case UREQ(UR_GET_STATUS, UT_READ_INTERFACE):
            case UREQ(UR_GET_STATUS, UT_READ_ENDPOINT):
                    DPRINTF(("umouse: (UR_GET_STATUS, UT_READ_INTERFACE)"));
                    if (data != NULL && len > 1) {
                            USETW(udata, 0);
                            data->blen = len - 2;
                            data->bdone += 2;
                    }
                    eshort = data->blen > 0;
                    break;

    There are actually four occurrences of this same bug, each in a
    different case in this switch block.

    Signed-off-by: Jack Bendtsen <jackdbendtsen@gmail.com>
    PR: 282237
    Reviewed by: imp, jhb, vexeduxr
    MFC After: 1 week
    Pull Request: https://github.com/freebsd/freebsd-src/pull/1728

 usr.sbin/bhyve/usb_mouse.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

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