* [PATCH bpf] bpf: fix bug in mmap() implementation for BPF array map
@ 2020-05-12 23:59 Andrii Nakryiko
2020-05-13 3:19 ` Yonghong Song
0 siblings, 1 reply; 3+ messages in thread
From: Andrii Nakryiko @ 2020-05-12 23:59 UTC (permalink / raw)
To: bpf, netdev, ast, daniel; +Cc: andrii.nakryiko, kernel-team, Andrii Nakryiko
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>
---
kernel/bpf/arraymap.c | 7 ++++++-
tools/testing/selftests/bpf/prog_tests/mmap.c | 8 ++++++++
2 files changed, 14 insertions(+), 1 deletion(-)
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;
--
2.24.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH bpf] bpf: fix bug in mmap() implementation for BPF array map
2020-05-12 23:59 [PATCH bpf] bpf: fix bug in mmap() implementation for BPF array map Andrii Nakryiko
@ 2020-05-13 3:19 ` Yonghong Song
2020-05-14 19:42 ` Alexei Starovoitov
0 siblings, 1 reply; 3+ messages in thread
From: Yonghong Song @ 2020-05-13 3:19 UTC (permalink / raw)
To: Andrii Nakryiko, bpf, netdev, ast, daniel; +Cc: andrii.nakryiko, kernel-team
On 5/12/20 4:59 PM, Andrii Nakryiko wrote:
> 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>
Acked-by: Yonghong Song <yhs@fb.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH bpf] bpf: fix bug in mmap() implementation for BPF array map
2020-05-13 3:19 ` Yonghong Song
@ 2020-05-14 19:42 ` Alexei Starovoitov
0 siblings, 0 replies; 3+ messages in thread
From: Alexei Starovoitov @ 2020-05-14 19:42 UTC (permalink / raw)
To: Yonghong Song
Cc: Andrii Nakryiko, bpf, Network Development, Alexei Starovoitov,
Daniel Borkmann, Andrii Nakryiko, Kernel Team
On Tue, May 12, 2020 at 8:21 PM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> On 5/12/20 4:59 PM, Andrii Nakryiko wrote:
> > 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>
> Acked-by: Yonghong Song <yhs@fb.com>
Applied. Thanks
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-05-12 23:59 [PATCH bpf] bpf: fix bug in mmap() implementation for BPF array map Andrii Nakryiko
2020-05-13 3:19 ` Yonghong Song
2020-05-14 19:42 ` Alexei Starovoitov
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