CVE-2026-93134: printk: Fix possible console use-after-free

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

printk: Fix possible console use-after-free

When emitting a record via legacy printing, it is possible that a handover to another legacy printing context occurs. When a context has performed a handover, the console SRCU read lock is released and the pointer to the console struct might now be invalid. Therefore, after calling nbconlegacyemitnextrecord() or consoleemitnextrecord(), it is necessary to check if a handover occurred before further @con usage.

Sashiko pointed out that consoleflushonerecord() was not doing this.

In consoleflushonerecord(), after emitting a record, move the further usage of @con after the handover check.