Re: [PATCH] tracing: Remove precision vsnprintf() check from print event

[Sachin Sant <sachinp@linux.ibm.com>]

> On 05-Mar-2024, at 4:13 AM, Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
> 
> 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@linux.ibm.com/
> Link: https://lore.kernel.org/linux-trace-kernel/20240227125706.04279ac2@gandalf.local.home
> Link: https://lore.kernel.org/all/20240302111244.3a1674be@gandalf.local.home/
> 
> Reported-by: Sachin Sant <sachinp@linux.ibm.com>
> Fixes: 60be76eeabb3d ("tracing: Add size check when printing trace_marker output")
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> ---

This fixes the reported problem for me.

All the ftrace selftests complete without any fails.
# of passed:  121
# of failed:  0
# of unresolved:  6
# of untested:  0
# of unsupported:  7
# of xfailed:  1
# of undefined(test bug):  0

Tested-by: Sachin Sant <sachinp@linux.ibm.com>


— Sachin