Messages in this thread Patch in this message | | | Date | Tue, 1 Jun 2021 16:56:50 +0100 | From | Luis Henriques <> | Subject | gcov: NULL pointer dereference with gcc 9.3.1 |
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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
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