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* [Bug analyzer/109106] New: GCC Static Analyzer doesn't model printf
@ 2023-03-12 13:08 geoffreydgr at icloud dot com
2023-03-12 14:35 ` [Bug analyzer/109106] " pinskia at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: geoffreydgr at icloud dot com @ 2023-03-12 13:08 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109106
Bug ID: 109106
Summary: GCC Static Analyzer doesn't model printf
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: geoffreydgr at icloud dot com
Target Milestone: ---
GCC Static Analyzer does not model `printf`.
see it live: https://godbolt.org/z/6ooW44sPq
Input:
```c
#include <stdio.h>
int main() {
int *j = 0;
printf("NPD_FLAG\n") || *j;
}
```
Output:
```
<source>: In function 'main':
<source>:10:27: warning: dereference of NULL 'j' [CWE-476]
[-Wanalyzer-null-dereference]
10 | printf("NPD_FLAG\n") || *j;
| ^~
'main': events 1-4
|
| 9 | int *j = 0;
| | ^
| | |
| | (1) 'j' is NULL
| 10 | printf("NPD_FLAG\n") || *j;
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~
| | | |
| | | (3) ...to here
| | | (4) dereference of NULL 'j'
| | (2) following 'false' branch...
|
Compiler returned: 0
```
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug analyzer/109106] GCC Static Analyzer doesn't model printf
2023-03-12 13:08 [Bug analyzer/109106] New: GCC Static Analyzer doesn't model printf geoffreydgr at icloud dot com
@ 2023-03-12 14:35 ` pinskia at gcc dot gnu.org
2023-03-12 19:40 ` pinskia at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-03-12 14:35 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109106
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
printf can still return 0.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug analyzer/109106] GCC Static Analyzer doesn't model printf
2023-03-12 13:08 [Bug analyzer/109106] New: GCC Static Analyzer doesn't model printf geoffreydgr at icloud dot com
2023-03-12 14:35 ` [Bug analyzer/109106] " pinskia at gcc dot gnu.org
@ 2023-03-12 19:40 ` pinskia at gcc dot gnu.org
2023-03-12 20:19 ` schwab@linux-m68k.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-03-12 19:40 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109106
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Why do you think printf will not return zero in some cases? Especially if
stdout is write fails.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug analyzer/109106] GCC Static Analyzer doesn't model printf
2023-03-12 13:08 [Bug analyzer/109106] New: GCC Static Analyzer doesn't model printf geoffreydgr at icloud dot com
2023-03-12 14:35 ` [Bug analyzer/109106] " pinskia at gcc dot gnu.org
2023-03-12 19:40 ` pinskia at gcc dot gnu.org
@ 2023-03-12 20:19 ` schwab@linux-m68k.org
2023-03-13 14:20 ` dmalcolm at gcc dot gnu.org
2023-07-19 17:11 ` geoffreydgr at icloud dot com
4 siblings, 0 replies; 6+ messages in thread
From: schwab@linux-m68k.org @ 2023-03-12 20:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109106
--- Comment #3 from Andreas Schwab <schwab@linux-m68k.org> ---
When an output error occurs it returns < 0. Only printf("") or printf("%s",
"") can return 0.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug analyzer/109106] GCC Static Analyzer doesn't model printf
2023-03-12 13:08 [Bug analyzer/109106] New: GCC Static Analyzer doesn't model printf geoffreydgr at icloud dot com
` (2 preceding siblings ...)
2023-03-12 20:19 ` schwab@linux-m68k.org
@ 2023-03-13 14:20 ` dmalcolm at gcc dot gnu.org
2023-07-19 17:11 ` geoffreydgr at icloud dot com
4 siblings, 0 replies; 6+ messages in thread
From: dmalcolm at gcc dot gnu.org @ 2023-03-13 14:20 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109106
David Malcolm <dmalcolm at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |DUPLICATE
--- Comment #4 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
Thanks for filing this, and for the comments; marking it as a dup of PR 107017
*** This bug has been marked as a duplicate of bug 107017 ***
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug analyzer/109106] GCC Static Analyzer doesn't model printf
2023-03-12 13:08 [Bug analyzer/109106] New: GCC Static Analyzer doesn't model printf geoffreydgr at icloud dot com
` (3 preceding siblings ...)
2023-03-13 14:20 ` dmalcolm at gcc dot gnu.org
@ 2023-07-19 17:11 ` geoffreydgr at icloud dot com
4 siblings, 0 replies; 6+ messages in thread
From: geoffreydgr at icloud dot com @ 2023-07-19 17:11 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109106
--- Comment #5 from Geoffrey <geoffreydgr at icloud dot com> ---
(In reply to David Malcolm from comment #4)
> Thanks for filing this, and for the comments; marking it as a dup of PR
> 107017
>
> *** This bug has been marked as a duplicate of bug 107017 ***
Hi, David. I want to ask a question that does GSA supports printf now?
The gcc online docs
(https://gcc.gnu.org/onlinedocs/gcc/Static-Analyzer-Options.html#index-fanalyzer-checker)
says that GSA has hardcoded knowledge about the behavior of this function. But
I find that GSA still cannot handle printf (see
https://godbolt.org/z/6ooW44sPq). Then I checked the source code, I find that
you have modeled `sprintf`.
I am wondering why GCC static analysis misses `printf`. IMO, it seems
straightforward to model. Or actually it is hard to model?
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-07-19 17:11 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-03-12 13:08 [Bug analyzer/109106] New: GCC Static Analyzer doesn't model printf geoffreydgr at icloud dot com
2023-03-12 14:35 ` [Bug analyzer/109106] " pinskia at gcc dot gnu.org
2023-03-12 19:40 ` pinskia at gcc dot gnu.org
2023-03-12 20:19 ` schwab@linux-m68k.org
2023-03-13 14:20 ` dmalcolm at gcc dot gnu.org
2023-07-19 17:11 ` geoffreydgr at icloud dot com
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