[v3] mem: fix the alloc size roundup overflow
Checks
Commit Message
The size checking is done in the caller. The size parameter is an
unsigned (64b wide) right now, so the comparison with zero should be
enough in most cases. But it won't help in the following case.
If the allocating request input a huge number by mistake, e.g., some
overflow after the calculation (especially subtraction), the checking
in the caller will succeed since it is not zero. Indeed, there is not
enough space in the system to support such huge memory allocation.
Usually it will return failure in the following code. But if the
input size is just a little smaller than the UINT64_MAX, like -2 in
signed type.
The roundup will cause an overflow and then "reset" the size to 0,
and then only a header (128B now) with zero length will be returned.
The following will be the previous allocation header.
It should be OK in most cases if the application won't access the
memory body. Or else, some critical issue will be caused and not easy
to debug. So this issue should be prevented at the beginning, like
other big size failure, NULL pointer should be returned also.
Fixes: fdf20fa7bee9 ("add prefix to cache line macros")
Cc: sergio.gonzalez.monroy@intel.com
Cc: stable@dpdk.org
Signed-off-by: Bing Zhao <bingz@mellanox.com>
---
v2: add unit test for this case
v3: fix the code style by using tab
---
app/test/test_malloc.c | 12 ++++++++++++
lib/librte_eal/common/malloc_heap.c | 3 +++
2 files changed, 15 insertions(+)
Comments
On Thu, May 7, 2020 at 10:03 AM Bing Zhao <bingz@mellanox.com> wrote:
>
> The size checking is done in the caller. The size parameter is an
> unsigned (64b wide) right now, so the comparison with zero should be
> enough in most cases. But it won't help in the following case.
> If the allocating request input a huge number by mistake, e.g., some
> overflow after the calculation (especially subtraction), the checking
> in the caller will succeed since it is not zero. Indeed, there is not
> enough space in the system to support such huge memory allocation.
> Usually it will return failure in the following code. But if the
> input size is just a little smaller than the UINT64_MAX, like -2 in
> signed type.
> The roundup will cause an overflow and then "reset" the size to 0,
> and then only a header (128B now) with zero length will be returned.
> The following will be the previous allocation header.
> It should be OK in most cases if the application won't access the
> memory body. Or else, some critical issue will be caused and not easy
> to debug. So this issue should be prevented at the beginning, like
> other big size failure, NULL pointer should be returned also.
>
> Fixes: fdf20fa7bee9 ("add prefix to cache line macros")
> Cc: stable@dpdk.org
>
> Signed-off-by: Bing Zhao <bingz@mellanox.com>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>
Applied, thanks.
@@ -846,6 +846,18 @@
if (bad_ptr != NULL)
goto err_return;
+ /* rte_malloc expected to return null with size will cause overflow */
+ align = RTE_CACHE_LINE_SIZE;
+ size = (size_t)-8;
+
+ bad_ptr = rte_malloc(type, size, align);
+ if (bad_ptr != NULL)
+ goto err_return;
+
+ bad_ptr = rte_realloc(NULL, size, align);
+ if (bad_ptr != NULL)
+ goto err_return;
+
return 0;
err_return:
@@ -241,6 +241,9 @@
size = RTE_CACHE_LINE_ROUNDUP(size);
align = RTE_CACHE_LINE_ROUNDUP(align);
+ /* roundup might cause an overflow */
+ if (size == 0)
+ return NULL;
elem = find_suitable_element(heap, size, flags, align, bound, contig);
if (elem != NULL) {
elem = malloc_elem_alloc(elem, size, align, bound, contig);