On Tue, Mar 08, 2022 at 12:28:59PM -0500, Oleg Drokin wrote:
> Hello!
>
> I am wondering why alloc_page and friends are not considering an allocation function?
> Found a bit of code where there was an obvious alloc_page leak that was not caught that is caught if I change alloc_page to kmalloc.
>
> And while trying to put the support into smatch I suddenly found the structure changed so much from the previous time I looked at it it’s very non-obvious how to add it.
>
> I tried adding hooks in check_free_strict.c, check_frees_argument.c, check_leaks.c, smatch_constraints_required.c, smatch_fresh_alloc.c, smatch_parse_call_math.c
> and tried to insert it alongside kmalloc in smatch_scripts/gen_allocation_list.sh and I still cannot make
> it work in the actual kernel code even though a modified testcase from validation/sm_memory.c works.
>
>
> Any hint?
The check_leaks.c function is really limitted in the type of leaks it
looks for. It has basically no false positives, but misses 90% of bugs.
If you're looking for leaks the right place to add it is probably in
check_unwind.c.
regards,
dan carpenter
diff --git a/check_unwind.c b/check_unwind.c
index 569792ad5a57..7ef040d2ca59 100644
--- a/check_unwind.c
+++ b/check_unwind.c
@@ -92,6 +92,10 @@ static struct ref_func_info func_table[] = {
{ "ieee80211_alloc_hw", ALLOC, -1, "$", &valid_ptr_min_sval, &valid_ptr_max_sval },
{ "ieee80211_free_hw", RELEASE, 0, "$" },
+
+ { "alloc_pages", ALLOC, -1, "$", &valid_ptr_min_sval, &valid_ptr_max_sval },
+ { "__get_free_pages", ALLOC, -1, "$", &valid_ptr_min_sval, &valid_ptr_max_sval },
+ { "free_pages", RELEASE, 0, "$" },
};
static struct smatch_state *unmatched_state(struct sm_state *sm)
