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* [Bug analyzer/109201] New: GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b = 1) / f)` where `f` is 0
@ 2023-03-19 16:52 geoffreydgr at icloud dot com
2023-03-20 20:07 ` [Bug analyzer/109201] " dmalcolm at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: geoffreydgr at icloud dot com @ 2023-03-19 16:52 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109201
Bug ID: 109201
Summary: GCC Static Analyzer does not generate a div-by-zero
warning for the `if ((d.b = 1) / f)` where `f` is 0
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 generate a div-by-zero warning for the `if ((d.b =
1) / f)` statement, but if it is changed to `if ((d.b = 1) / 0)`, analyzer
generates that warning.
See it live: https://godbolt.org/z/3f18j9az7
Input:
```c
void __analyzer_eval();
struct a
{
int b : 6;
} c()
{
struct a d;
int e = 2;
int f = 0;
if ((d.b = 1) / f)
if (1 >= d.b <= e)
{
__analyzer_eval(0 >= d.b <= e);
}
}
```
Output:
```
<source>: In function 'c':
<source>:15:13: warning: TRUE
15 | __analyzer_eval(0 >= d.b <= e);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Compiler returned: 0
```
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug analyzer/109201] GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b = 1) / f)` where `f` is 0
2023-03-19 16:52 [Bug analyzer/109201] New: GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b = 1) / f)` where `f` is 0 geoffreydgr at icloud dot com
@ 2023-03-20 20:07 ` dmalcolm at gcc dot gnu.org
2023-03-20 20:08 ` dmalcolm at gcc dot gnu.org
2023-03-20 20:13 ` dmalcolm at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: dmalcolm at gcc dot gnu.org @ 2023-03-20 20:07 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109201
--- Comment #1 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
The division by zero warning on:
if ((d.b = 1) / 0)
is from -Wdiv-by-zero, which isn't from the analyzer (
https://godbolt.org/z/433PhKhvM )
The analyzer currently only implements -Wanalyzer-tainted-divisor for
attacker-controlled values used in division; it doesn't check for zero itself.
So this seems like more of an RFE: it sounds like you'd want the analyzer to
complain about known zero values reaching a division, as a souped-up kind
implementation of the existing -Wdiv-by-zero.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug analyzer/109201] GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b = 1) / f)` where `f` is 0
2023-03-19 16:52 [Bug analyzer/109201] New: GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b = 1) / f)` where `f` is 0 geoffreydgr at icloud dot com
2023-03-20 20:07 ` [Bug analyzer/109201] " dmalcolm at gcc dot gnu.org
@ 2023-03-20 20:08 ` dmalcolm at gcc dot gnu.org
2023-03-20 20:13 ` dmalcolm at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: dmalcolm at gcc dot gnu.org @ 2023-03-20 20:08 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109201
--- Comment #2 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
*** Bug 109200 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug analyzer/109201] GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b = 1) / f)` where `f` is 0
2023-03-19 16:52 [Bug analyzer/109201] New: GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b = 1) / f)` where `f` is 0 geoffreydgr at icloud dot com
2023-03-20 20:07 ` [Bug analyzer/109201] " dmalcolm at gcc dot gnu.org
2023-03-20 20:08 ` dmalcolm at gcc dot gnu.org
@ 2023-03-20 20:13 ` dmalcolm at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: dmalcolm at gcc dot gnu.org @ 2023-03-20 20:13 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109201
David Malcolm <dmalcolm at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |DUPLICATE
Status|UNCONFIRMED |RESOLVED
--- Comment #3 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
We already have PR 99669 as an RFE for this; marking as a dup.
*** This bug has been marked as a duplicate of bug 99669 ***
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-03-20 20:13 UTC | newest]
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2023-03-19 16:52 [Bug analyzer/109201] New: GCC Static Analyzer does not generate a div-by-zero warning for the `if ((d.b = 1) / f)` where `f` is 0 geoffreydgr at icloud dot com
2023-03-20 20:07 ` [Bug analyzer/109201] " dmalcolm at gcc dot gnu.org
2023-03-20 20:08 ` dmalcolm at gcc dot gnu.org
2023-03-20 20:13 ` dmalcolm at gcc dot gnu.org
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