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


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


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