linux/tools/lib/subcmd/subcmd-util.h
Kees Cook 52a9dab6d8 libsubcmd: Fix use-after-free for realloc(..., 0)
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")
Reported-by: Valdis Klētnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Kees Kook <keescook@chromium.org>
Tested-by: Valdis Klētnieks <valdis.kletnieks@vt.edu>
Tested-by: Justin M. Forbes <jforbes@fedoraproject.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: linux-hardening@vger.kernel.org
Cc: Valdis Klētnieks <valdis.kletnieks@vt.edu>
Link: http://lore.kernel.org/lkml/20220213182443.4037039-1-keescook@chromium.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-02-16 13:49:25 -03:00

77 lines
1.7 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __SUBCMD_UTIL_H
#define __SUBCMD_UTIL_H
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#define NORETURN __attribute__((__noreturn__))
static inline void report(const char *prefix, const char *err, va_list params)
{
char msg[1024];
vsnprintf(msg, sizeof(msg), err, params);
fprintf(stderr, " %s%s\n", prefix, msg);
}
static NORETURN inline void die(const char *err, ...)
{
va_list params;
va_start(params, err);
report(" Fatal: ", err, params);
exit(128);
va_end(params);
}
#define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
#define alloc_nr(x) (((x)+16)*3/2)
/*
* Realloc the buffer pointed at by variable 'x' so that it can hold
* at least 'nr' entries; the number of entries currently allocated
* is 'alloc', using the standard growing factor alloc_nr() macro.
*
* DO NOT USE any expression with side-effect for 'x' or 'alloc'.
*/
#define ALLOC_GROW(x, nr, alloc) \
do { \
if ((nr) > alloc) { \
if (alloc_nr(alloc) < (nr)) \
alloc = (nr); \
else \
alloc = alloc_nr(alloc); \
x = xrealloc((x), alloc * sizeof(*(x))); \
} \
} while(0)
static inline void *xrealloc(void *ptr, size_t size)
{
void *ret = realloc(ptr, size);
if (!ret)
die("Out of memory, realloc failed");
return ret;
}
#define astrcatf(out, fmt, ...) \
({ \
char *tmp = *(out); \
if (asprintf((out), "%s" fmt, tmp ?: "", ## __VA_ARGS__) == -1) \
die("asprintf failed"); \
free(tmp); \
})
static inline void astrcat(char **out, const char *add)
{
char *tmp = *out;
if (asprintf(out, "%s%s", tmp ?: "", add) == -1)
die("asprintf failed");
free(tmp);
}
#endif /* __SUBCMD_UTIL_H */