[v2] mem: poison memory when freed
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Commit Message
DPDK malloc library allows broken programs to work because
the semantics of zmalloc and malloc are the same.
This patch enables a more secure model which will catch
(and crash) programs that reuse memory already freed if
RTE_MALLOC_DEBUG is enabled.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Andrew Rybchenko <arybchenko@solarflare.com>
Reviewed-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
v2 -- fix #ifdef to get correct semantics, and add more comments
lib/librte_eal/common/malloc_elem.c | 18 +++++++++++++++---
lib/librte_eal/common/rte_malloc.c | 13 ++++++++++++-
2 files changed, 27 insertions(+), 4 deletions(-)
Comments
16/02/2019 02:50, Stephen Hemminger:
> DPDK malloc library allows broken programs to work because
> the semantics of zmalloc and malloc are the same.
>
> This patch enables a more secure model which will catch
> (and crash) programs that reuse memory already freed if
> RTE_MALLOC_DEBUG is enabled.
>
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> Acked-by: Andrew Rybchenko <arybchenko@solarflare.com>
> Reviewed-by: Anatoly Burakov <anatoly.burakov@intel.com>
Applied, thanks
@@ -23,6 +23,17 @@
#include "malloc_elem.h"
#include "malloc_heap.h"
+/*
+ * If debugging is enabled, freed memory is set to poison value
+ * to catch buggy programs. Otherwise, freed memory is set to zero
+ * to avoid having to zero in zmalloc
+ */
+#ifdef RTE_MALLOC_DEBUG
+#define MALLOC_POISON 0x6b
+#else
+#define MALLOC_POISON 0
+#endif
+
size_t
malloc_elem_find_max_iova_contig(struct malloc_elem *elem, size_t align)
{
@@ -494,7 +505,7 @@ malloc_elem_join_adjacent_free(struct malloc_elem *elem)
join_elem(elem, elem->next);
/* erase header, trailer and pad */
- memset(erase, 0, erase_len);
+ memset(erase, MALLOC_POISON, erase_len);
}
/*
@@ -518,7 +529,7 @@ malloc_elem_join_adjacent_free(struct malloc_elem *elem)
join_elem(new_elem, elem);
/* erase header, trailer and pad */
- memset(erase, 0, erase_len);
+ memset(erase, MALLOC_POISON, erase_len);
elem = new_elem;
}
@@ -549,7 +560,8 @@ malloc_elem_free(struct malloc_elem *elem)
/* decrease heap's count of allocated elements */
elem->heap->alloc_count--;
- memset(ptr, 0, data_len);
+ /* poison memory */
+ memset(ptr, MALLOC_POISON, data_len);
return elem;
}
@@ -74,7 +74,18 @@ rte_malloc(const char *type, size_t size, unsigned align)
void *
rte_zmalloc_socket(const char *type, size_t size, unsigned align, int socket)
{
- return rte_malloc_socket(type, size, align, socket);
+ void *ptr = rte_malloc_socket(type, size, align, socket);
+
+#ifdef RTE_MALLOC_DEBUG
+ /*
+ * If DEBUG is enabled, then freed memory is marked with poison
+ * value and set to zero on allocation.
+ * If DEBUG is not enabled then memory is already zeroed.
+ */
+ if (ptr != NULL)
+ memset(ptr, 0, size);
+#endif
+ return ptr;
}
/*