CVE-2022-49065

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

SUNRPC: Fix the svcdeferredevent trace class

Fix a NULL deref crash that occurs when an svcrqst is deferred while the sunrpc tracing subsystem is enabled. svcrevisit() sets dr->xprt to NULL, so it can't be relied upon in the tracepoint to provide the remote's address.

Unfortunately we can't revert the "svcdeferredclass" hunk in commit ece200ddd54b ("sunrpc: Save remote presentation address in svc_xprt for trace events") because there is now a specific check of event format specifiers for unsafe dereferences. The warning that check emits is:

event svcdeferrecv has unsafe dereference of argument 1

A "%pISpc" format specifier with a "struct sockaddr *" is indeed flagged by this check.

Instead, take the brute-force approach used by the svcrdmaqperror tracepoint. Convert the dr::addr field into a presentation address in the TPfastassign() arm of the trace event, and store that as a string. This fix can be backported to -stable kernels.

In the meantime, commit c6ced22997ad ("tracing: Update print fmt check to handle new __get_sockaddr() macro") is now in v5.18, so this wonky fix can be replaced with __sockaddr() and friends properly during the v5.19 merge window.