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* [Bug middle-end/101475] New: missing -Wstringop-overflow storing a compound literal
@ 2021-07-16 16:58 msebor at gcc dot gnu.org
  2021-12-16 18:28 ` [Bug middle-end/101475] " msebor at gcc dot gnu.org
                   ` (3 more replies)
  0 siblings, 4 replies; 5+ messages in thread
From: msebor at gcc dot gnu.org @ 2021-07-16 16:58 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101475

            Bug ID: 101475
           Summary: missing -Wstringop-overflow storing a compound literal
           Product: gcc
           Version: 11.1.0
            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: ---

Even with pr97027 resolved -Wstringop-overflow is not issued consistently (on
all targets) for buffer overflow when storing a larger compound literal into a
smaller buffer.  The test case below is diagnosed by -Warray-bounds which is
only enabled with -Wall and at -O2, but not by -Wstringop-overflow (which is
enabled by default).  Ideally the bug should be diagnosed even at -O0.

$ cat a.c && gcc -O2 -S -fdump-tree-strlen=/dev/stdout a.c 
typedef struct A { char a[4]; } A;

extern char a[2];

void f (void)
{
  *(A*)a = (A){ 1, 2, 3, 4 };   // missing warning
}

typedef struct B { int a[2]; } B;

void g (void)
{
  *(B*)a = (B){ 1, 2 };   // missing warning
}

;; Function f (f, funcdef_no=0, decl_uid=3910, cgraph_uid=1, symbol_order=0)

;; 1 loops found
;;
;; Loop 0
;;  header 0, latch 1
;;  depth 0, outer -1
;;  nodes: 0 1 2
;; 2 succs { 1 }
void f ()
{
  <bb 2> [local count: 1073741824]:
  MEM[(struct A *)&a].a[0] = 1;
  MEM[(struct A *)&a].a[1] = 2;
  MEM[(struct A *)&a].a[2] = 3;
  MEM[(struct A *)&a].a[3] = 4;
  return;

}



;; Function g (g, funcdef_no=1, decl_uid=3917, cgraph_uid=2, symbol_order=1)

;; 1 loops found
;;
;; Loop 0
;;  header 0, latch 1
;;  depth 0, outer -1
;;  nodes: 0 1 2
;; 2 succs { 1 }
void g ()
{
  <bb 2> [local count: 1073741824]:
  MEM[(struct B *)&a].a[0] = 1;
  MEM[(struct B *)&a].a[1] = 2;
  return;

}

^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-01-14 18:15 UTC | newest]

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2021-07-16 16:58 [Bug middle-end/101475] New: missing -Wstringop-overflow storing a compound literal msebor at gcc dot gnu.org
2021-12-16 18:28 ` [Bug middle-end/101475] " msebor at gcc dot gnu.org
2021-12-16 19:57 ` msebor at gcc dot gnu.org
2022-01-14 18:14 ` cvs-commit at gcc dot gnu.org
2022-01-14 18:15 ` msebor at gcc dot gnu.org

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