lkml.org 
[lkml]   [2021]   [Jun]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subjectgcov: NULL pointer dereference with gcc 9.3.1
Hi!

Maybe this is a known (gcc?) issue, but I'm seeing a NULL pointer splat if
I instrument my kernel (or a module, more specifically) using gcc 9.3.1.

It looks like, during initialization in __gcov_init(), gcov_info struct is
invalid: the filename seems to be correct but ->function is NULL and
->n_functions contains garbage. This will result in the NULL pointer if,
for example, I run:

# echo 1 > /sys/kernel/debug/gcov/reset

Other installed gcc versions (7.5.0 and 10.3.0) work fine.

Is this a know issue with this specific gcc versions? Anyway, it may
be worth having something like (not tested!):

diff --git a/kernel/gcov/gcc_base.c b/kernel/gcov/gcc_base.c
index 3cf736b9f880..de3ea47f4f62 100644
--- a/kernel/gcov/gcc_base.c
+++ b/kernel/gcov/gcc_base.c
@@ -13,6 +13,11 @@ void __gcov_init(struct gcov_info *info)
{
static unsigned int gcov_version;

+ if (!info || !info->functions) {
+ pr_err_once("Invalid gcov_info structure\n");
+ return;
+ }
+
mutex_lock(&gcov_lock);
if (gcov_version == 0) {
gcov_version = gcov_info_version(info);
And also something similar in the clang code, I guess.

I can send a real (tested) patch if you wish, but I just wanted to know if
I'm missing something first.

Cheers,
--
Luis

\
 
 \ /
  Last update: 2021-06-01 17:57    [W:0.146 / U:0.320 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site