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libsubcmd: Fix use-after-free for realloc(..., 0) 

Bugzilla: https://bugzilla.redhat.com/2069073

upstream
========
commit 52a9dab6d892763b2a8334a568bd4e2c1a6fde66
Author: Kees Cook <keescook@chromium.org>
Date: Sun Feb 13 10:24:43 2022 -0800

description
===========
GCC 12 correctly reports a potential use-after-free condition in the
xrealloc helper. Fix the warning by avoiding an implicit "free(ptr)"
when size == 0:

In file included from help.c:12:
In function 'xrealloc',
    inlined from 'add_cmdname' at help.c:24:2: subcmd-util.h:56:23: error: pointer may be used after 'realloc' [-Werror=use-after-free]
   56 |                 ret = realloc(ptr, size);
      |                       ^~~~~~~~~~~~~~~~~~
subcmd-util.h:52:21: note: call to 'realloc' here
   52 |         void *ret = realloc(ptr, size);
      |                     ^~~~~~~~~~~~~~~~~~
subcmd-util.h:58:31: error: pointer may be used after 'realloc' [-Werror=use-after-free]
   58 |                         ret = realloc(ptr, 1);
      |                               ^~~~~~~~~~~~~~~
subcmd-util.h:52:21: note: call to 'realloc' here
   52 |         void *ret = realloc(ptr, size);
      |                     ^~~~~~~~~~~~~~~~~~

Fixes: 2f4ce5ec1d ("perf tools: Finalize subcmd independence")

Signed-off-by: Michael Petlan <mpetlan@redhat.com>
This commit is contained in:
Michael Petlan 2022-05-03 22:01:44 +02:00
parent 89495da366
commit e426c83c96
1 changed files with 2 additions and 9 deletions
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11
tools/lib/subcmd/subcmd-util.h
View File

@ -50,15 +50,8 @@ static NORETURN inline void die(const char *err, ...)
static inline void *xrealloc(void *ptr, size_t size)
{
void *ret = realloc(ptr, size);
if (!ret && !size)
ret = realloc(ptr, 1);
if (!ret) {
ret = realloc(ptr, size);
if (!ret && !size)
ret = realloc(ptr, 1);
if (!ret)
die("Out of memory, realloc failed");
}
if (!ret)
die("Out of memory, realloc failed");
return ret;
}