lkml.org 
[lkml]   [2023]   [Nov]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v1 04/12] dyndbg: add 2 trace-events: pr_debug, dev_dbg
On Fri,  3 Nov 2023 14:10:03 +0100
Łukasz Bartosik <lb@semihalf.com> wrote:

> +/* capture pr_debug() callsite descriptor and message */
> +TRACE_EVENT(prdbg,
> + TP_PROTO(const struct _ddebug *desc, const char *text, size_t len),
> +
> + TP_ARGS(desc, text, len),
> +
> + TP_STRUCT__entry(
> + __field(const struct _ddebug *, desc)
> + __dynamic_array(char, msg, len + 1)
> + ),
> +
> + TP_fast_assign(
> + __entry->desc = desc;
> + /*
> + * Each trace entry is printed in a new line.
> + * If the msg finishes with '\n', cut it off
> + * to avoid blank lines in the trace.
> + */
> + if (len > 0 && (text[len - 1] == '\n'))
> + len -= 1;
> +
> + memcpy(__get_str(msg), text, len);
> + __get_str(msg)[len] = 0;
> + ),
> +


> + TP_printk("%s.%s %s", __entry->desc->modname,
> + __entry->desc->function, __get_str(msg))
> +);
> +

That TP_printk() is dangerous. How do you know __entry->desc still exists
when reading the buffer?

Is the struct _ddebug permanent? Can it be freed? If so, the above can
easily cause a crash.

-- Steve

\
 
 \ /
  Last update: 2023-11-20 13:50    [W:0.226 / U:0.044 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site