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* [Bug middle-end/96925] New: missing warning on sprintf into destination at negative offset
@ 2020-09-03 16:03 msebor at gcc dot gnu.org
2020-09-03 16:06 ` [Bug middle-end/96925] " msebor at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: msebor at gcc dot gnu.org @ 2020-09-03 16:03 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96925
Bug ID: 96925
Summary: missing warning on sprintf into destination at
negative offset
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
Only the first of the two invalid calls below is diagnosed. Both should be.
$ cat z.c && gcc -O2 -S -Wall -xc -fdump-tree-optimized=/dev/stdout z.c
extern char a[];
void f (int i)
{
if (i >= 0) i = -1;
__builtin_strcpy (a + i, "3"); // warning (good)
}
void g (int i)
{
if (i >= 0) i = -1;
__builtin_sprintf (a + i, "%i", 3); // missing warning
}
z.c: In function ‘f’:
z.c:6:3: warning: ‘__builtin_memcpy’ offset [-2147483648, -1] is out of the
bounds of object ‘a’ with type ‘char[]’ [-Warray-bounds]
6 | __builtin_strcpy (a + i, "3"); // warning (good)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
z.c:1:13: note: ‘a’ declared here
1 | extern char a[];
| ^
;; Function f (f, funcdef_no=0, decl_uid=1931, cgraph_uid=1, symbol_order=0)
f (int i)
{
sizetype _1;
char * _2;
<bb 2> [local count: 1073741824]:
i_4 = MIN_EXPR <i_3(D), -1>;
_1 = (sizetype) i_4;
_2 = &a + _1;
__builtin_memcpy (_2, "3", 2); [tail call]
return;
}
;; Function g (g, funcdef_no=1, decl_uid=1934, cgraph_uid=2, symbol_order=1)
g (int i)
{
sizetype _1;
char * _2;
<bb 2> [local count: 1073741824]:
i_4 = MIN_EXPR <i_3(D), -1>;
_1 = (sizetype) i_4;
_2 = &a + _1;
__builtin_sprintf (_2, "%i", 3); [tail call]
return;
}
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug middle-end/96925] missing warning on sprintf into destination at negative offset
2020-09-03 16:03 [Bug middle-end/96925] New: missing warning on sprintf into destination at negative offset msebor at gcc dot gnu.org
@ 2020-09-03 16:06 ` msebor at gcc dot gnu.org
0 siblings, 0 replies; 2+ messages in thread
From: msebor at gcc dot gnu.org @ 2020-09-03 16:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96925
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Blocks| |56456
Keywords| |diagnostic
--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
The warning for the strcpy is issued by the wrestrict pass which doesn't
consider sprintf. -Wrestrict is implemented separately for sprintf but without
the same bounds checking.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56456
[Bug 56456] [meta-bug] bogus/missing -Warray-bounds
^ permalink raw reply [flat|nested] 2+ messages in thread
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2020-09-03 16:03 [Bug middle-end/96925] New: missing warning on sprintf into destination at negative offset msebor at gcc dot gnu.org
2020-09-03 16:06 ` [Bug middle-end/96925] " msebor at gcc dot gnu.org
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