In the Linux kernel, the following vulnerability has been resolved:
serial: core: fix infinite loop in handletx() for PORTUNKNOWN
uartwriteroom() and uartwrite() behave inconsistently when xmitbuf is NULL (which happens for PORT_UNKNOWN ports that were never properly initialized):
This inconsistency causes an infinite loop in drivers that rely on ttywriteroom() to determine if they can write:
while (ttywriteroom(tty) > 0) { written = tty->ops->write(...); // written is always 0, loop never exits }
For example, caifserial's handletx() enters an infinite loop when used with PORT_UNKNOWN serial ports, causing system hangs.
Fix by making uartwriteroom() also check xmitbuf and return 0 if it's NULL, consistent with uartwrite().
Reproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13
{
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23472.json",
"cna_assigner": "Linux"
}