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BACKPORT: bpf: Fix bug in mmap() implementation for BPF array map

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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")
Change-Id: I3655caa80db06740f738ec9366b018cd389919ed
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
This commit is contained in:
Andrii Nakryiko 2020-05-12 16:59:25 -07:00 • committed by basamaryan
commit 159faaf366
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1 changed files with 6 additions and 1 deletions
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7
kernel/bpf/arraymap.c
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@ -489,7 +489,12 @@ 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 = {