Patch "tracing: Remove precision vsnprintf() check from print event" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    tracing: Remove precision vsnprintf() check from print event

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tracing-remove-precision-vsnprintf-check-from-print-.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 34571f1426ba9c2239b21a925bff300acc3b5ef5
Author: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Date:   Mon Mar 4 17:43:41 2024 -0500

    tracing: Remove precision vsnprintf() check from print event
    
    [ Upstream commit 5efd3e2aef91d2d812290dcb25b2058e6f3f532c ]
    
    This reverts 60be76eeabb3d ("tracing: Add size check when printing
    trace_marker output"). The only reason the precision check was added
    was because of a bug that miscalculated the write size of the string into
    the ring buffer and it truncated it removing the terminating nul byte. On
    reading the trace it crashed the kernel. But this was due to the bug in
    the code that happened during development and should never happen in
    practice. If anything, the precision can hide bugs where the string in the
    ring buffer isn't nul terminated and it will not be checked.
    
    Link: https://lore.kernel.org/all/C7E7AF1A-D30F-4D18-B8E5-AF1EF58004F5@xxxxxxxxxxxxx/
    Link: https://lore.kernel.org/linux-trace-kernel/20240227125706.04279ac2@xxxxxxxxxxxxxxxxxx
    Link: https://lore.kernel.org/all/20240302111244.3a1674be@xxxxxxxxxxxxxxxxxx/
    Link: https://lore.kernel.org/linux-trace-kernel/20240304174341.2a561d9f@xxxxxxxxxxxxxxxxxx
    
    Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
    Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
    Fixes: 60be76eeabb3d ("tracing: Add size check when printing trace_marker output")
    Reported-by: Sachin Sant <sachinp@xxxxxxxxxxxxx>
    Tested-by: Sachin Sant <sachinp@xxxxxxxxxxxxx>
    Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
    Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 43fb832d26d23..62015d62dd6f5 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -1320,12 +1320,11 @@ static enum print_line_t trace_print_print(struct trace_iterator *iter,
 {
 	struct print_entry *field;
 	struct trace_seq *s = &iter->seq;
-	int max = iter->ent_size - offsetof(struct print_entry, buf);
 
 	trace_assign_type(field, iter->ent);
 
 	seq_print_ip_sym(s, field->ip, flags);
-	trace_seq_printf(s, ": %.*s", max, field->buf);
+	trace_seq_printf(s, ": %s", field->buf);
 
 	return trace_handle_return(s);
 }
@@ -1334,11 +1333,10 @@ static enum print_line_t trace_print_raw(struct trace_iterator *iter, int flags,
 					 struct trace_event *event)
 {
 	struct print_entry *field;
-	int max = iter->ent_size - offsetof(struct print_entry, buf);
 
 	trace_assign_type(field, iter->ent);
 
-	trace_seq_printf(&iter->seq, "# %lx %.*s", field->ip, max, field->buf);
+	trace_seq_printf(&iter->seq, "# %lx %s", field->ip, field->buf);
 
 	return trace_handle_return(&iter->seq);
 }