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* [Bug c++/95354] New: GCC misuse "nonnull-attribute" option and can not detect it as UB as well
@ 2020-05-27 4:25 haoxintu at gmail dot com
2020-05-27 4:50 ` [Bug c++/95354] " pinskia at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: haoxintu at gmail dot com @ 2020-05-27 4:25 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95354
Bug ID: 95354
Summary: GCC misuse "nonnull-attribute" option and can not
detect it as UB as well
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: haoxintu at gmail dot com
Target Milestone: ---
This case test.cc
#include<iostream>
#include<cstddef>
void has_nonnull_argument(__attribute__((nonnull)) int *p) {
;
}
int main () {
has_nonnull_argument(NULL);
std::cout << "ok" << std::endl;
return 0;
}
in GCC-trunk
$./g++ -fsanitize=undefined test.cc ; ./a.out
test.cc:3:57: warning: ‘nonnull’ attribute only applies to function types
[-Wattributes]
3 | void has_nonnull_argument(__attribute__((nonnull)) int *p) {
| ^
ok
$./g++ -fsanitize=nonull-attribute test.cc ; ./a.out
test.cc:3:57: warning: ‘nonnull’ attribute only applies to function types
[-Wattributes]
3 | void has_nonnull_argument(__attribute__((nonnull)) int *p) {
| ^
ok
in Clang-trunk
$clang++ -fsanitize=nonnull-attribute test.cc ; ./a.out
est.cc:7:30: warning: null passed to a callee that requires a non-null argument
[-Wnonnull]
has_nonnull_argument(NULL);
~~~~^
1 warning generated.
test.cc:7:26: runtime error: null pointer passed as argument 1, which is
declared to never be null
test.cc:3:42: note: nonnull attribute specified here
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior test.cc:7:26 in
ok
According to the description in
https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options
for "-fsanitize=nonull-attribute", it says "This option enables instrumentation
of calls, checking whether null values are not passed to arguments marked as
requiring a non-null value by the nonnull function attribute."
I guess the warning message by GCC may also incorrect, the correct one should
look like in Clang produced.
I have tested them in recent GCC versions including GCC-8, GCC-9, and GCC-10,
they have the same symptom as well.
My GCC version is
$g++ --version
g++ (GCC) 11.0.0 20200526 (experimental)
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/95354] GCC misuse "nonnull-attribute" option and can not detect it as UB as well
2020-05-27 4:25 [Bug c++/95354] New: GCC misuse "nonnull-attribute" option and can not detect it as UB as well haoxintu at gmail dot com
@ 2020-05-27 4:50 ` pinskia at gcc dot gnu.org
2020-05-27 9:16 ` redi at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2020-05-27 4:50 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95354
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |INVALID
Status|UNCONFIRMED |RESOLVED
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
No,
The place where nonnull attribute is not on the argument itself but rather on
the function.
See the document at:
https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Common-Function-Attributes.html#index-nonnull-function-attribute
THIS IS WHY GCC Is warning on that pointer and all.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/95354] GCC misuse "nonnull-attribute" option and can not detect it as UB as well
2020-05-27 4:25 [Bug c++/95354] New: GCC misuse "nonnull-attribute" option and can not detect it as UB as well haoxintu at gmail dot com
2020-05-27 4:50 ` [Bug c++/95354] " pinskia at gcc dot gnu.org
@ 2020-05-27 9:16 ` redi at gcc dot gnu.org
2020-05-27 9:32 ` haoxintu at gmail dot com
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2020-05-27 9:16 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95354
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Allowing the attribute on individual parameters might be nice though.
I hate the fact that for C++ member functions the first parameter is the
implicit 'this' pointer which always has to be non-null anyway.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/95354] GCC misuse "nonnull-attribute" option and can not detect it as UB as well
2020-05-27 4:25 [Bug c++/95354] New: GCC misuse "nonnull-attribute" option and can not detect it as UB as well haoxintu at gmail dot com
2020-05-27 4:50 ` [Bug c++/95354] " pinskia at gcc dot gnu.org
2020-05-27 9:16 ` redi at gcc dot gnu.org
@ 2020-05-27 9:32 ` haoxintu at gmail dot com
2020-05-27 10:46 ` redi at gcc dot gnu.org
2020-05-27 11:43 ` haoxintu at gmail dot com
4 siblings, 0 replies; 6+ messages in thread
From: haoxintu at gmail dot com @ 2020-05-27 9:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95354
--- Comment #3 from Haoxin Tu <haoxintu at gmail dot com> ---
I see. Are there any cases that can trigger the UB of nonnull-attribute? I
doubt the usage of “-fsanitize=nonnull-attribute” in GCC...
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/95354] GCC misuse "nonnull-attribute" option and can not detect it as UB as well
2020-05-27 4:25 [Bug c++/95354] New: GCC misuse "nonnull-attribute" option and can not detect it as UB as well haoxintu at gmail dot com
` (2 preceding siblings ...)
2020-05-27 9:32 ` haoxintu at gmail dot com
@ 2020-05-27 10:46 ` redi at gcc dot gnu.org
2020-05-27 11:43 ` haoxintu at gmail dot com
4 siblings, 0 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2020-05-27 10:46 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95354
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Haoxin Tu from comment #3)
> I see. Are there any cases that can trigger the UB of nonnull-attribute? I
> doubt the usage of “-fsanitize=nonnull-attribute” in GCC...
Yes, just use the attribute correctly.
Using:
__attribute__((nonnull)) void has_nonnull_argument(int *p) {
;
}
will cause UBsan to diagnose it:
nn.cc:7:25: runtime error: null pointer passed as argument 1, which is declared
to never be null
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/95354] GCC misuse "nonnull-attribute" option and can not detect it as UB as well
2020-05-27 4:25 [Bug c++/95354] New: GCC misuse "nonnull-attribute" option and can not detect it as UB as well haoxintu at gmail dot com
` (3 preceding siblings ...)
2020-05-27 10:46 ` redi at gcc dot gnu.org
@ 2020-05-27 11:43 ` haoxintu at gmail dot com
4 siblings, 0 replies; 6+ messages in thread
From: haoxintu at gmail dot com @ 2020-05-27 11:43 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95354
--- Comment #5 from Haoxin Tu <haoxintu at gmail dot com> ---
(In reply to Jonathan Wakely from comment #4)
> (In reply to Haoxin Tu from comment #3)
> > I see. Are there any cases that can trigger the UB of nonnull-attribute? I
> > doubt the usage of “-fsanitize=nonnull-attribute” in GCC...
>
> Yes, just use the attribute correctly.
>
> Using:
>
> __attribute__((nonnull)) void has_nonnull_argument(int *p) {
> ;
> }
>
> will cause UBsan to diagnose it:
>
> nn.cc:7:25: runtime error: null pointer passed as argument 1, which is
> declared to never be null
Thanks, Jonathan, Got it ~
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-05-27 11:43 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2020-05-27 4:25 [Bug c++/95354] New: GCC misuse "nonnull-attribute" option and can not detect it as UB as well haoxintu at gmail dot com
2020-05-27 4:50 ` [Bug c++/95354] " pinskia at gcc dot gnu.org
2020-05-27 9:16 ` redi at gcc dot gnu.org
2020-05-27 9:32 ` haoxintu at gmail dot com
2020-05-27 10:46 ` redi at gcc dot gnu.org
2020-05-27 11:43 ` haoxintu at gmail dot com
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