CVE-2024-46676

In the Linux kernel, the following vulnerability has been resolved:

nfc: pn533: Add poll mod list filling check

In case of improtocols value is 1 and tmprotocols value is 0 this combination successfully passes the check 'if (!improtocols && !tmprotocols)' in the nfcstartpoll(). But then after pn533pollcreatemodlist() call in pn533startpoll() poll mod list will remain empty and dev->pollmodcount will remain 0 which lead to division by zero.

Normally no im protocol has value 1 in the mask, so this combination is not expected by driver. But these protocol values actually come from userspace via Netlink interface (NFCCMDSTARTPOLL operation). So a broken or malicious program may pass a message containing a "bad" combination of protocol parameter values so that dev->pollmodcount is not incremented inside pn533pollcreatemodlist(), thus leading to division by zero. Call trace looks like: nfcgenlstartpoll() nfcstartpoll() ->startpoll() pn533start_poll()

Add poll mod list filling check.

Found by Linux Verification Center (linuxtesting.org) with SVACE.