[v2,3/7] malloc: Ensure that the consolidated fast chunk has a sane size.

Message ID 1510068430-27816-4-git-send-email-pistukem@gmail.com
State New
Headers show
Series
  • Additional integrity checks for the malloc
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Commit Message

Istvan Kurucsai Nov. 7, 2017, 3:27 p.m.
* malloc/malloc.c (malloc_consolidate): Add size check.
---
 malloc/malloc.c | 5 +++++
 1 file changed, 5 insertions(+)

Comments

Florian Weimer Jan. 12, 2018, 2:28 p.m. | #1
On 11/07/2017 04:27 PM, Istvan Kurucsai wrote:
>      * malloc/malloc.c (malloc_consolidate): Add size check.
> ---
>   malloc/malloc.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/malloc/malloc.c b/malloc/malloc.c
> index d3fac7e..51d703c 100644
> --- a/malloc/malloc.c
> +++ b/malloc/malloc.c
> @@ -4406,6 +4406,7 @@ static void malloc_consolidate(mstate av)
>     mfastbinptr*    fb;                 /* current fastbin being consolidated */
>     mfastbinptr*    maxfb;              /* last fastbin (for loop control) */
>     mchunkptr       p;                  /* current chunk being consolidated */
> +  unsigned int    idx;                /* fastbin index of current chunk */
>     mchunkptr       nextp;              /* next chunk to consolidate */
>     mchunkptr       unsorted_bin;       /* bin header */
>     mchunkptr       first_unsorted;     /* chunk to link to */
> @@ -4437,6 +4438,10 @@ static void malloc_consolidate(mstate av)
>       p = atomic_exchange_acq (fb, NULL);
>       if (p != 0) {
>         do {
> +	idx = fastbin_index (chunksize (p));
> +	if ((&fastbin (av, idx)) != fb)
> +	  malloc_printerr ("malloc_consolidate(): invalid chunk size");
> +

This looks good.  I'm going to minimize the scope for idx and push this.

Thanks,
Florian

Patch

diff --git a/malloc/malloc.c b/malloc/malloc.c
index d3fac7e..51d703c 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -4406,6 +4406,7 @@  static void malloc_consolidate(mstate av)
   mfastbinptr*    fb;                 /* current fastbin being consolidated */
   mfastbinptr*    maxfb;              /* last fastbin (for loop control) */
   mchunkptr       p;                  /* current chunk being consolidated */
+  unsigned int    idx;                /* fastbin index of current chunk */
   mchunkptr       nextp;              /* next chunk to consolidate */
   mchunkptr       unsorted_bin;       /* bin header */
   mchunkptr       first_unsorted;     /* chunk to link to */
@@ -4437,6 +4438,10 @@  static void malloc_consolidate(mstate av)
     p = atomic_exchange_acq (fb, NULL);
     if (p != 0) {
       do {
+	idx = fastbin_index (chunksize (p));
+	if ((&fastbin (av, idx)) != fb)
+	  malloc_printerr ("malloc_consolidate(): invalid chunk size");
+
 	check_inuse_chunk(av, p);
 	nextp = p->fd;