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bpf, xskmap: fix crash in xsk_map_alloc error path handling

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If bpf_map_precharge_memlock() did not fail, then we set err to zero.
However, any subsequent failure from either alloc_percpu() or the
bpf_map_area_alloc() will return ERR_PTR(0) which in find_and_alloc_map()
will cause NULL pointer deref.

In devmap we have the convention that we return -EINVAL on page count
overflow, so keep the same logic here and just set err to -ENOMEM
after successful bpf_map_precharge_memlock().

Fixes: fbfc504a24 ("bpf: introduce new bpf AF_XDP map type BPF_MAP_TYPE_XSKMAP")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Björn Töpel <bjorn.topel@intel.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Daniel Borkmann 2018-05-04 16:27:53 +02:00 committed by Alexei Starovoitov
parent a5458aa923
commit e94fa1d931
1 changed files with 2 additions and 0 deletions
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2
kernel/bpf/xskmap.c
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@ -56,6 +56,8 @@ static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
if (err)
goto free_m;
err = -ENOMEM;
m->flush_list = alloc_percpu(struct list_head);
if (!m->flush_list)
goto free_m;