[PATCH:xrdb] Use reallocarray() for array allocations & resizing

[Matthieu Herrb]

On Sat, Aug 08, 2015 at 09:04:44AM -0700, Alan Coopersmith wrote:
> Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>
Reviewed-by: Matthieu Herrb <matthieu at herrb.eu>

> ---
>  configure.ac |    2 +-
>  xrdb.c       |   39 +++++++++++++++++++++++++++++++++------
>  2 files changed, 34 insertions(+), 7 deletions(-)
> 
> diff --git a/configure.ac b/configure.ac
> index bf7e0a7..2c42add 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -37,7 +37,7 @@ m4_ifndef([XORG_MACROS_VERSION],
>  XORG_MACROS_VERSION(1.8)
>  XORG_DEFAULT_OPTIONS
>  
> -AC_CHECK_FUNCS([mkstemp asprintf])
> +AC_CHECK_FUNCS([mkstemp asprintf reallocarray])
>  
>  # Find MAXHOSTNAMELEN definition
>  # Common hidey holes:
> diff --git a/xrdb.c b/xrdb.c
> index a980230..72e526c 100644
> --- a/xrdb.c
> +++ b/xrdb.c
> @@ -53,6 +53,7 @@
>  #include <errno.h>
>  #include <stdlib.h>
>  #include <stdarg.h>
> +#include <stdint.h>
>  
>  #ifdef NEED_SYS_PARAM_H
>  # include <sys/param.h>         /* defines MAXHOSTNAMELEN on BSD & Linux */
> @@ -186,12 +187,27 @@ asprintf(char **ret, const char *format, ...)
>  }
>  #endif                          /* HAVE_ASPRINTF */
>  
> +#ifndef HAVE_REALLOCARRAY
> +/* overflow checking realloc API from OpenBSD libc */
> +static inline void *
> +reallocarray(void *optr, size_t n, size_t s)
> +{
> +    if (n > 0 && (SIZE_MAX / n) < s)
> +        return NULL;
> +    return realloc(optr, n * s);
> +}
> +#endif
> +
> +# define mallocarray(n, s) reallocarray(NULL, n, s)
> +
>  static void
>  InitBuffer(Buffer *b)
>  {
>      b->room = INIT_BUFFER_SIZE;
>      b->used = 0;
> -    b->buff = malloc(INIT_BUFFER_SIZE * sizeof(char));
> +    b->buff = mallocarray(INIT_BUFFER_SIZE, sizeof(char));
> +    if (b->buff == NULL)
> +        fatal("%s: Can't allocate memory in %s\n", ProgramName, __func__);
>  }
>  
>  #ifdef notyet
> @@ -206,7 +222,9 @@ static void
>  AppendToBuffer(Buffer *b, const char *str, size_t len)
>  {
>      while (b->used + len > b->room) {
> -        b->buff = realloc(b->buff, 2 * b->room * (sizeof(char)));
> +        b->buff = reallocarray(b->buff, b->room, 2 * sizeof(char));
> +        if (b->buff == NULL)
> +            fatal("%s: Can't allocate memory in %s\n", ProgramName, __func__);
>          b->room *= 2;
>      }
>      strncpy(b->buff + b->used, str, len);
> @@ -218,7 +236,10 @@ InitEntries(Entries *e)
>  {
>      e->room = INIT_ENTRY_SIZE;
>      e->used = 0;
> -    e->entry = malloc(INIT_ENTRY_SIZE * sizeof(Entry));
> +    e->entry = mallocarray(INIT_ENTRY_SIZE, sizeof(Entry));
> +    if (e->entry == NULL)
> +        fatal("%s: Can't allocate memory in %s\n", ProgramName, __func__);
> +
>  }
>  
>  static void
> @@ -258,7 +279,9 @@ AddEntry(Entries *e, Entry *entry)
>      }
>  
>      if (e->used == e->room) {
> -        e->entry = realloc(e->entry, 2 * e->room * (sizeof(Entry)));
> +        e->entry = reallocarray(e->entry, e->room, 2 * sizeof(Entry));
> +        if (e->entry == NULL)
> +            fatal("%s: Can't allocate memory in %s\n", ProgramName, __func__);
>          e->room *= 2;
>      }
>      entry->usable = True;
> @@ -1141,7 +1164,9 @@ main(int argc, char *argv[])
>      else {
>          Entries *dbs;
>  
> -        dbs = malloc(((unsigned) ScreenCount(dpy)) * sizeof(Entries));
> +        dbs = mallocarray(ScreenCount(dpy), sizeof(Entries));
> +        if (dbs == NULL)
> +            fatal("%s: Can't allocate memory in %s\n", ProgramName, __func__);
>          for (i = 0; i < ScreenCount(dpy); i++) {
>              Process(i, True, False);
>              dbs[i] = newDB;
> @@ -1425,7 +1450,9 @@ ShuffleEntries(Entries *db, Entries *dbs, unsigned int num)
>      Entries cur, cmp;
>      char *curtag, *curvalue;
>  
> -    hits = malloc(num * sizeof(int));
> +    hits = mallocarray(num, sizeof(int));
> +    if (hits == NULL)
> +        fatal("%s: Can't allocate memory in %s\n", ProgramName, __func__);
>      cur = dbs[0];
>      for (i = 0; i < cur.used; i++) {
>          curtag = cur.entry[i].tag;
> -- 
> 1.7.9.2
> 
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-- 
Matthieu Herrb