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authorAndrii Nakryiko <andriin@fb.com>2020-05-12 16:59:25 -0700
committerAlexei Starovoitov <ast@kernel.org>2020-05-14 12:40:04 -0700
commit333291ce5055f2039afc907badaf5b66bc1adfdc (patch)
tree27c603d11355ab26e741a267cf52b112b70a91b5
parent23ad04669f81f958e9a4121b0266228d2eb3c357 (diff)
bpf: Fix bug in mmap() implementation for BPF array map
mmap() subsystem allows user-space application to memory-map region with initial page offset. This wasn't taken into account in initial implementation of BPF array memory-mapping. This would result in wrong pages, not taking into account requested page shift, being memory-mmaped into user-space. This patch fixes this gap and adds a test for such scenario. Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY") Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200512235925.3817805-1-andriin@fb.com
-rw-r--r--kernel/bpf/arraymap.c7
-rw-r--r--tools/testing/selftests/bpf/prog_tests/mmap.c8
2 files changed, 14 insertions, 1 deletions
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 95d77770353c..1d6120fd5ba6 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -486,7 +486,12 @@ static int array_map_mmap(struct bpf_map *map, struct vm_area_struct *vma)
if (!(map->map_flags & BPF_F_MMAPABLE))
return -EINVAL;
- return remap_vmalloc_range(vma, array_map_vmalloc_addr(array), pgoff);
+ if (vma->vm_pgoff * PAGE_SIZE + (vma->vm_end - vma->vm_start) >
+ PAGE_ALIGN((u64)array->map.max_entries * array->elem_size))
+ return -EINVAL;
+
+ return remap_vmalloc_range(vma, array_map_vmalloc_addr(array),
+ vma->vm_pgoff + pgoff);
}
const struct bpf_map_ops array_map_ops = {
diff --git a/tools/testing/selftests/bpf/prog_tests/mmap.c b/tools/testing/selftests/bpf/prog_tests/mmap.c
index 56d80adcf4bd..6b9dce431d41 100644
--- a/tools/testing/selftests/bpf/prog_tests/mmap.c
+++ b/tools/testing/selftests/bpf/prog_tests/mmap.c
@@ -217,6 +217,14 @@ void test_mmap(void)
munmap(tmp2, 4 * page_size);
+ /* map all 4 pages, but with pg_off=1 page, should fail */
+ tmp1 = mmap(NULL, 4 * page_size, PROT_READ, MAP_SHARED | MAP_FIXED,
+ data_map_fd, page_size /* initial page shift */);
+ if (CHECK(tmp1 != MAP_FAILED, "adv_mmap7", "unexpected success")) {
+ munmap(tmp1, 4 * page_size);
+ goto cleanup;
+ }
+
tmp1 = mmap(NULL, map_sz, PROT_READ, MAP_SHARED, data_map_fd, 0);
if (CHECK(tmp1 == MAP_FAILED, "last_mmap", "failed %d\n", errno))
goto cleanup;