[Bug middle-end/101475] New: missing -Wstringop-overflow storing a compound literal

[Bug middle-end/101475] New: missing -Wstringop-overflow storing a compound literal

[msebor at gcc dot gnu.org]

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;

}

[Bug middle-end/101475] missing -Wstringop-overflow storing a compound literal

[msebor at gcc dot gnu.org]

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

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |crazylht at gmail dot com

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
*** Bug 102722 has been marked as a duplicate of this bug. ***

[Bug middle-end/101475] missing -Wstringop-overflow storing a compound literal

[msebor at gcc dot gnu.org]

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

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2021-12-16
     Ever confirmed|0                           |1
   Target Milestone|---                         |12.0
           Keywords|                            |patch
           Assignee|unassigned at gcc dot gnu.org      |msebor at gcc dot gnu.org

--- Comment #2 from Martin Sebor <msebor at gcc dot gnu.org> ---
Patch: https://gcc.gnu.org/pipermail/gcc-patches/2021-December/587033.html

[Bug middle-end/101475] missing -Wstringop-overflow storing a compound literal

[cvs-commit at gcc dot gnu.org]

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

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Martin Sebor <msebor@gcc.gnu.org>:

https://gcc.gnu.org/g:72332337e3d8acbb21398b8d123f1bfe77a8327e

commit r12-6592-g72332337e3d8acbb21398b8d123f1bfe77a8327e
Author: Martin Sebor <msebor@redhat.com>
Date:   Fri Jan 14 11:13:08 2022 -0700

    Use enclosing object size if it's smaller than member [PR 101475].

    Resolves:
    PR middle-end/101475 - missing -Wstringop-overflow storing a compound
literal

    gcc/ChangeLog:

            PR middle-end/101475
            * pointer-query.cc (handle_component_ref): Use the size of
            the enclosing object if it's smaller than the member.

    gcc/testsuite/ChangeLog:

            PR middle-end/101475
            * gcc.dg/Wstringop-overflow-15.c: Remove xfails.
            * gcc.dg/Wstringop-overflow-68.c: Adjust, remove xfails.
            * gcc.dg/Wstringop-overflow-88.c: New test.

[Bug middle-end/101475] missing -Wstringop-overflow storing a compound literal

[msebor at gcc dot gnu.org]

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

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #4 from Martin Sebor <msebor at gcc dot gnu.org> ---
Fixed in r12-6592.