HID: core: Fix assumption that Resolution Multipliers must be in Logical Collections

JIRA: https://issues.redhat.com/browse/RHEL-81477
CVE: CVE-2024-57986

commit 64f2657
Author: Alan Stern <stern@rowland.harvard.edu>
Date:   Tue Dec 31 14:23:12 2024 -0500

    HID: core: Fix assumption that Resolution Multipliers must be in Logical Collections

    A report in 2019 by the syzbot fuzzer was found to be connected to two
    errors in the HID core associated with Resolution Multipliers.  One of
    the errors was fixed by commit ea427a2 ("HID: core: Fix deadloop
    in hid_apply_multiplier."), but the other has not been fixed.

    This error arises because hid_apply_multipler() assumes that every
    Resolution Multiplier control is contained in a Logical Collection,
    i.e., there's no way the routine can ever set multiplier_collection to
    NULL.  This is in spite of the fact that the function starts with a
    big comment saying:

             * "The Resolution Multiplier control must be contained in the same
             * Logical Collection as the control(s) to which it is to be applied.
               ...
             *  If no Logical Collection is
             * defined, the Resolution Multiplier is associated with all
             * controls in the report."
             * HID Usage Table, v1.12, Section 4.3.1, p30
             *
             * Thus, search from the current collection upwards until we find a
             * logical collection...

    The comment and the code overlook the possibility that none of the
    collections found may be a Logical Collection.

    The fix is to set the multiplier_collection pointer to NULL if the
    collection found isn't a Logical Collection.

    Reported-by: syzbot+ec5f884c4a135aa0dbb9@syzkaller.appspotmail.com
    Closes: https://lore.kernel.org/all/000000000000109c040597dc5843@google.com/
    Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
    Cc: Peter Hutterer <peter.hutterer@who-t.net>
    Fixes: 5a4abb3 ("HID: core: process the Resolution Multiplier")
    Cc: stable@vger.kernel.org
    Signed-off-by: Jiri Kosina <jkosina@suse.com>

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

Author: CKI Backport Bot

drivers/hid/hid-core.c

@@ -1125,6 +1125,8 @@ static void hid_apply_multiplier(struct hid_device *hid,
 	while (multiplier_collection->parent_idx != -1 &&
 	       multiplier_collection->type != HID_COLLECTION_LOGICAL)
 		multiplier_collection = &hid->collection[multiplier_collection->parent_idx];
+	if (multiplier_collection->type != HID_COLLECTION_LOGICAL)
+		multiplier_collection = NULL;
 
 	effective_multiplier = hid_calculate_multiplier(hid, multiplier);