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ftrace: Replaces simple_strtoul in ftrace 

The function simple_strtoul performs no error checking in scenarios
where the input value overflows the intended output variable.
This results in this function successfully returning, even when the
output does not match the input string (aka the function returns
successfully even when the result is wrong).

Or as it was mentioned [1], "...simple_strtol(), simple_strtoll(),
simple_strtoul(), and simple_strtoull() functions explicitly ignore
overflows, which may lead to unexpected results in callers."
Hence, the use of those functions is discouraged.

This patch replaces all uses of the simple_strtoul with the safer
alternatives kstrtoul and kstruint.

Callers affected:
- add_rec_by_index
- set_graph_max_depth_function

Side effects of this patch:
- Since `fgraph_max_depth` is an `unsigned int`, this patch uses
  kstrtouint instead of kstrtoul to avoid any compiler warnings
  that could originate from calling the latter.
- This patch ensures that the callers of kstrtou* return accordingly
  when kstrtoul and kstruint fail for some reason.
  In this case, both callers this patch is addressing return 0 on error.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#simple-strtol-simple-strtoll-simple-strtoul-simple-strtoull

Link: https://lore.kernel.org/linux-trace-kernel/GV1PR10MB656333529A8D7B8AFB28D238E8B4A@GV1PR10MB6563.EURPRD10.PROD.OUTLOOK.COM

Signed-off-by: Yuran Pereira <yuran.pereira@hotmail.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Yuran Pereira 2023-11-20 05:46:13 +05:30 committed by Steven Rostedt (Google)
parent dd5a440a31
commit c5963a0990
1 changed files with 3 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
kernel/trace/ftrace.c
View File

@ -4202,12 +4202,12 @@ static int
add_rec_by_index(struct ftrace_hash *hash, struct ftrace_glob *func_g,
int clear_filter)
{
long index = simple_strtoul(func_g->search, NULL, 0);
long index;
struct ftrace_page *pg;
struct dyn_ftrace *rec;
/* The index starts at 1 */
if (--index < 0)
if (kstrtoul(func_g->search, 0, &index) || --index < 0)
return 0;
do_for_each_ftrace_rec(pg, rec) {
@ -5817,9 +5817,8 @@ __setup("ftrace_graph_notrace=", set_graph_notrace_function);
static int __init set_graph_max_depth_function(char *str)
{
if (!str)
if (!str || kstrtouint(str, 0, &fgraph_max_depth))
return 0;
fgraph_max_depth = simple_strtoul(str, NULL, 0);
return 1;
}
__setup("ftrace_graph_max_depth=", set_graph_max_depth_function);