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bpf: Fix values type used in test_maps 

Maps of per-cpu type have their value element size adjusted to 8 if it
is specified smaller during various map operations.

This makes test_maps as a 32-bit binary fail, in fact the kernel
writes past the end of the value's array on the user's stack.

To be quite honest, I think the kernel should reject creation of a
per-cpu map that doesn't have a value size of at least 8 if that's
what the kernel is going to silently adjust to later.

If the user passed something smaller, it is a sizeof() calcualtion
based upon the type they will actually use (just like in this testcase
code) in later calls to the map operations.

Fixes: df570f5772 ("samples/bpf: unit test for BPF_MAP_TYPE_PERCPU_ARRAY")
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
David Miller 2017-04-20 15:20:16 -04:00 committed by David S. Miller
parent 557c44be91
commit 89087c456f
1 changed files with 2 additions and 2 deletions
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4
tools/testing/selftests/bpf/test_maps.c
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@ -282,7 +282,7 @@ static void test_arraymap_percpu(int task, void *data)
{ {
unsigned int nr_cpus = bpf_num_possible_cpus(); unsigned int nr_cpus = bpf_num_possible_cpus();
int key, next_key, fd, i; int key, next_key, fd, i;
long values[nr_cpus]; long long values[nr_cpus];
fd = bpf_create_map(BPF_MAP_TYPE_PERCPU_ARRAY, sizeof(key), fd = bpf_create_map(BPF_MAP_TYPE_PERCPU_ARRAY, sizeof(key),
sizeof(values[0]), 2, 0); sizeof(values[0]), 2, 0);
@ -340,7 +340,7 @@ static void test_arraymap_percpu_many_keys(void)
* allocator more than anything else * allocator more than anything else
*/ */
unsigned int nr_keys = 2000; unsigned int nr_keys = 2000;
long values[nr_cpus]; long long values[nr_cpus];
int key, fd, i; int key, fd, i;
fd = bpf_create_map(BPF_MAP_TYPE_PERCPU_ARRAY, sizeof(key), fd = bpf_create_map(BPF_MAP_TYPE_PERCPU_ARRAY, sizeof(key),