The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 4d38328eb442dc06aec4350fd9594ffa6488af02 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025040851-snowstorm-anyhow-9887@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4d38328eb442dc06aec4350fd9594ffa6488af02 Mon Sep 17 00:00:00 2001 From: Douglas Raillard douglas.raillard@arm.com Date: Tue, 25 Mar 2025 16:52:02 +0000 Subject: [PATCH] tracing: Fix synth event printk format for str fields

The printk format for synth event uses "%.*s" to print string fields, but then only passes the pointer part as var arg.

Replace %.*s with %s as the C string is guaranteed to be null-terminated.

The output in print fmt should never have been updated as __get_str() handles the string limit because it can access the length of the string in the string meta data that is saved in the ring buffer.

Cc: stable@vger.kernel.org Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Mathieu Desnoyers mathieu.desnoyers@efficios.com Fixes: 8db4d6bfbbf92 ("tracing: Change synthetic event string format to limit printed length") Link: https://lore.kernel.org/20250325165202.541088-1-douglas.raillard@arm.com Signed-off-by: Douglas Raillard douglas.raillard@arm.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c index a5c5f34c207a..6d592cbc38e4 100644 --- a/kernel/trace/trace_events_synth.c +++ b/kernel/trace/trace_events_synth.c @@ -305,7 +305,7 @@ static const char *synth_field_fmt(char *type) else if (strcmp(type, "gfp_t") == 0) fmt = "%x"; else if (synth_field_is_string(type)) - fmt = "%.*s"; + fmt = "%s"; else if (synth_field_is_stack(type)) fmt = "%s";