On Tue, 2026-06-30 at 18:54 -0400, Steven Rostedt wrote:

From: Steven Rostedt <rostedt@goodmis.org>

The trace events in drivers/ufs/core/ufs_trace.h were converted to
take a
pointer to the hba structure as an argument for the tracepoint and
then in
TP_printk() the printing of the dev_name from the ring buffer was
converted to using the dev dereferenced pointer from the hba saved
pointer.

This is not allowed as the TP_printk() is executed at the time the
trace
event is read from /sys/kernel/tracing/trace file. That can happen
literally, seconds, minutes, hours, weeks, days, or even months
later!
There is no guarantee that the hba pointer will still exist by the
time it
is dereferenced when the "trace" file is read.

Instead, save the device name from the hba pointer at the time the
tracepoint is called and place it into the ring buffer event. Then
the
TP_printk() can read the name directly from the ring buffer and
remove the
possibility that it will read a freed pointer and crash the kernel.

This was detected when testing the trace event code that looks for
TP_printk() parameters doing illegal derferences[1]

[1]
https://lore.kernel.org/all/20260630184836.74d477b6@gandalf.local.home/ (local)

Cc: stable@vger.kernel.org
Fixes: 583e518e71003 ("scsi: ufs: core: Add hba parameter to trace
events")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Reviewed-by: Peter Wang <peter.wang@mediatek.com>