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* [Bug analyzer/107345] New: - -Wanayzer-null-dereference false positive with giving weird path infomation
@ 2022-10-21 9:52 geoffreydgr at icloud dot com
2022-10-24 14:35 ` [Bug analyzer/107345] " dmalcolm at gcc dot gnu.org
` (6 more replies)
0 siblings, 7 replies; 8+ messages in thread
From: geoffreydgr at icloud dot com @ 2022-10-21 9:52 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107345
Bug ID: 107345
Summary: - -Wanayzer-null-dereference false positive with
giving weird path infomation
Product: gcc
Version: 12.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: geoffreydgr at icloud dot com
Target Milestone: ---
I got a weird false positive error when compiling the following "minimal,
complete and verifiable example (MCVE)" program.
```
#include <stdio.h>
int main() {
int e = 10086;
int *f = &e;
int g = 0;
int *h[2][1];
h[1][0] = f;
if (g == (h[1][0])) {
// printf("if true\n");
unsigned int *i = 0;
}
printf("NPD_FLAG: %d\n ", *f);
return 0;
}
```
Compiling the above code with gcc 12.1 with `-O0 -fanalyzer` in
https://godbolt.org/z/av4beszh7 results in :
```
<source>: In function 'main':
<source>:8:9: warning: comparison between pointer and integer
8 | if (g == (h[1][0])) {
| ^~
<source>:12:3: warning: dereference of NULL 'f' [CWE-476]
[-Wanalyzer-null-dereference]
12 | printf("NPD_FLAG: %d\n ", *f);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'main': events 1-4
|
| 8 | if (g == (h[1][0])) {
| | ^
| | |
| | (1) following 'true' branch...
| 9 | // printf("if true\n");
| 10 | unsigned int *i = 0;
| | ~
| | |
| | (2) ...to here
| | (3) '&e' is NULL
| 11 | }
| 12 | printf("NPD_FLAG: %d\n ", *f);
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (4) dereference of NULL 'f'
|
```
It is obvious that dereference of 'f' at line 12 cannot result in NPD. It is
weird that the tool reports "(3) '&e' is NULL" at line 10. There is even no
'&e' there.
But if i change the original program to the following one, the NPD false
positive goes away.
```
#include <stdio.h>
int main() {
int e = 10086;
int *f = &e;
int g = 0;
int *h[2][1];
h[1][0] = f;
if (g == (f)) {
// printf("if true\n");
unsigned int *i = 0;
}
printf("NPD_FLAG: %d\n ", *f);
return 0;
}
```
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug analyzer/107345] - -Wanayzer-null-dereference false positive with giving weird path infomation
2022-10-21 9:52 [Bug analyzer/107345] New: - -Wanayzer-null-dereference false positive with giving weird path infomation geoffreydgr at icloud dot com
@ 2022-10-24 14:35 ` dmalcolm at gcc dot gnu.org
2022-10-24 20:49 ` cvs-commit at gcc dot gnu.org
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: dmalcolm at gcc dot gnu.org @ 2022-10-24 14:35 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107345
David Malcolm <dmalcolm at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2022-10-24
--- Comment #1 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
Thanks for filing this bug. The analyzer is seeing
NULL == &e
and fails to treat this as being false; the logic for spotting comparison of
&VAR against NULL was only looking for NULL on the right-hand side.
I'm working on a fix.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug analyzer/107345] - -Wanayzer-null-dereference false positive with giving weird path infomation
2022-10-21 9:52 [Bug analyzer/107345] New: - -Wanayzer-null-dereference false positive with giving weird path infomation geoffreydgr at icloud dot com
2022-10-24 14:35 ` [Bug analyzer/107345] " dmalcolm at gcc dot gnu.org
@ 2022-10-24 20:49 ` cvs-commit at gcc dot gnu.org
2022-10-24 21:02 ` dmalcolm at gcc dot gnu.org
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-10-24 20:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107345
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by David Malcolm <dmalcolm@gcc.gnu.org>:
https://gcc.gnu.org/g:18faaeb3af42f3d7dc609b9b91df77d0d59b16f6
commit r13-3468-g18faaeb3af42f3d7dc609b9b91df77d0d59b16f6
Author: David Malcolm <dmalcolm@redhat.com>
Date: Mon Oct 24 16:38:23 2022 -0400
analyzer: handle (NULL == &VAR) [PR107345]
gcc/analyzer/ChangeLog:
PR analyzer/107345
* region-model.cc (region_model::eval_condition_without_cm):
Ensure that constants are on the right-hand side before checking
for them.
gcc/testsuite/ChangeLog:
PR analyzer/107345
* gcc.dg/analyzer/pr107345.c: New test.
Signed-off-by: David Malcolm <dmalcolm@redhat.com>
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug analyzer/107345] - -Wanayzer-null-dereference false positive with giving weird path infomation
2022-10-21 9:52 [Bug analyzer/107345] New: - -Wanayzer-null-dereference false positive with giving weird path infomation geoffreydgr at icloud dot com
2022-10-24 14:35 ` [Bug analyzer/107345] " dmalcolm at gcc dot gnu.org
2022-10-24 20:49 ` cvs-commit at gcc dot gnu.org
@ 2022-10-24 21:02 ` dmalcolm at gcc dot gnu.org
2022-10-28 15:54 ` geoffreydgr at icloud dot com
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: dmalcolm at gcc dot gnu.org @ 2022-10-24 21:02 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107345
--- Comment #3 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
Fixed on trunk for GCC 13 by the above patch.
Keeping open for backporting to GCC 12.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug analyzer/107345] - -Wanayzer-null-dereference false positive with giving weird path infomation
2022-10-21 9:52 [Bug analyzer/107345] New: - -Wanayzer-null-dereference false positive with giving weird path infomation geoffreydgr at icloud dot com
` (2 preceding siblings ...)
2022-10-24 21:02 ` dmalcolm at gcc dot gnu.org
@ 2022-10-28 15:54 ` geoffreydgr at icloud dot com
2022-10-28 15:56 ` geoffreydgr at icloud dot com
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: geoffreydgr at icloud dot com @ 2022-10-28 15:54 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107345
--- Comment #4 from Geoffrey <geoffreydgr at icloud dot com> ---
(In reply to David Malcolm from comment #3)
> Fixed on trunk for GCC 13 by the above patch.
>
> Keeping open for backporting to GCC 12.
That is really great! Thanks a lot!
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug analyzer/107345] - -Wanayzer-null-dereference false positive with giving weird path infomation
2022-10-21 9:52 [Bug analyzer/107345] New: - -Wanayzer-null-dereference false positive with giving weird path infomation geoffreydgr at icloud dot com
` (3 preceding siblings ...)
2022-10-28 15:54 ` geoffreydgr at icloud dot com
@ 2022-10-28 15:56 ` geoffreydgr at icloud dot com
2023-03-29 18:18 ` [Bug analyzer/107345] -Wanalyzer-null-dereference " cvs-commit at gcc dot gnu.org
2023-03-29 19:15 ` dmalcolm at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: geoffreydgr at icloud dot com @ 2022-10-28 15:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107345
--- Comment #5 from Geoffrey <geoffreydgr at icloud dot com> ---
(In reply to David Malcolm from comment #3)
> Fixed on trunk for GCC 13 by the above patch.
>
> Keeping open for backporting to GCC 12.
That is really great! Thanks a lot!
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug analyzer/107345] -Wanalyzer-null-dereference false positive with giving weird path infomation
2022-10-21 9:52 [Bug analyzer/107345] New: - -Wanayzer-null-dereference false positive with giving weird path infomation geoffreydgr at icloud dot com
` (4 preceding siblings ...)
2022-10-28 15:56 ` geoffreydgr at icloud dot com
@ 2023-03-29 18:18 ` cvs-commit at gcc dot gnu.org
2023-03-29 19:15 ` dmalcolm at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2023-03-29 18:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107345
--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by David Malcolm
<dmalcolm@gcc.gnu.org>:
https://gcc.gnu.org/g:111fb5d3cafd0f7f2a0d01aa9e1213013fa0cc83
commit r12-9357-g111fb5d3cafd0f7f2a0d01aa9e1213013fa0cc83
Author: David Malcolm <dmalcolm@redhat.com>
Date: Wed Mar 29 14:16:47 2023 -0400
analyzer: handle (NULL == &VAR) [PR107345]
Cherrypicked from r13-3468-g18faaeb3af42f3.
gcc/analyzer/ChangeLog:
PR analyzer/107345
* region-model.cc (region_model::eval_condition_without_cm):
Ensure that constants are on the right-hand side before checking
for them.
gcc/testsuite/ChangeLog:
PR analyzer/107345
* gcc.dg/analyzer/pr107345.c: New test.
Signed-off-by: David Malcolm <dmalcolm@redhat.com>
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug analyzer/107345] -Wanalyzer-null-dereference false positive with giving weird path infomation
2022-10-21 9:52 [Bug analyzer/107345] New: - -Wanayzer-null-dereference false positive with giving weird path infomation geoffreydgr at icloud dot com
` (5 preceding siblings ...)
2023-03-29 18:18 ` [Bug analyzer/107345] -Wanalyzer-null-dereference " cvs-commit at gcc dot gnu.org
@ 2023-03-29 19:15 ` dmalcolm at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: dmalcolm at gcc dot gnu.org @ 2023-03-29 19:15 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107345
David Malcolm <dmalcolm at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|ASSIGNED |RESOLVED
--- Comment #7 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
Should be fixed on gcc 12 branch by the above (for the eventual gcc 12.3
release); marking as resolved.
^ permalink raw reply [flat|nested] 8+ messages in thread
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2022-10-21 9:52 [Bug analyzer/107345] New: - -Wanayzer-null-dereference false positive with giving weird path infomation geoffreydgr at icloud dot com
2022-10-24 14:35 ` [Bug analyzer/107345] " dmalcolm at gcc dot gnu.org
2022-10-24 20:49 ` cvs-commit at gcc dot gnu.org
2022-10-24 21:02 ` dmalcolm at gcc dot gnu.org
2022-10-28 15:54 ` geoffreydgr at icloud dot com
2022-10-28 15:56 ` geoffreydgr at icloud dot com
2023-03-29 18:18 ` [Bug analyzer/107345] -Wanalyzer-null-dereference " cvs-commit at gcc dot gnu.org
2023-03-29 19:15 ` dmalcolm at gcc dot gnu.org
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