Merge: CVE-2025-38556: HID: core: Harden s32ton() against conversion to 0 bits

MR: https://gitlab.com/redhat/rhel/src/kernel/rhel-10/-/merge_requests/282

JIRA: https://issues.redhat.com/browse/RHEL-111038
CVE: CVE-2025-38556

```
commit a6b87bf
Author: Alan Stern <stern@rowland.harvard.edu>
Date:   Wed Jul 23 10:37:04 2025 -0400

    HID: core: Harden s32ton() against conversion to 0 bits

    Testing by the syzbot fuzzer showed that the HID core gets a
    shift-out-of-bounds exception when it tries to convert a 32-bit
    quantity to a 0-bit quantity.  Ideally this should never occur, but
    there are buggy devices and some might have a report field with size
    set to zero; we shouldn't reject the report or the device just because
    of that.

    Instead, harden the s32ton() routine so that it returns a reasonable
    result instead of crashing when it is called with the number of bits
    set to 0 -- the same as what snto32() does.

    Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
    Reported-by: syzbot+b63d677d63bcac06cf90@syzkaller.appspotmail.com
    Closes: https://lore.kernel.org/linux-usb/68753a08.050a0220.33d347.0008.GAE@google.com/
    Tested-by: syzbot+b63d677d63bcac06cf90@syzkaller.appspotmail.com
    Fixes: dde5845 ("[PATCH] Generic HID layer - code split")
    Cc: stable@vger.kernel.org
    Link: https://patch.msgid.link/613a66cd-4309-4bce-a4f7-2905f9bce0c9@rowland.harvard.edu
    Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
```

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

Approved-by: Bastien Nocera <bnocera@redhat.com>
Approved-by: Tony Camuso <tcamuso@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Julio Faracco <jfaracco@redhat.com>

Author: jcfaracco

drivers/hid/hid-core.c

@@ -66,8 +66,12 @@ static s32 snto32(__u32 value, unsigned int n)
 
 static u32 s32ton(__s32 value, unsigned int n)
 {
-	s32 a = value >> (n - 1);
+	s32 a;
 
+	if (!value || !n)
+		return 0;
+
+	a = value >> (n - 1);
 	if (a && a != -1)
 		return value < 0 ? 1 << (n - 1) : (1 << (n - 1)) - 1;
 	return value & ((1 << n) - 1);