The nla_for_each_nested parsing in function bpf_sk_storage_diag_alloc
does not check the length of the nested attribute. This can lead to an
out-of-attribute read and allow a malformed nlattr (e.g., length 0) to
be viewed as a 4 byte integer.
This patch adds additional check before the execution of nla_get_u32 to
make sure the attribute has enough length.
Fixes: 1ed4d92458a9 ("bpf: INET_DIAG support in bpf_sk_storage")
Signed-off-by: Lin Ma <linma@xxxxxxxxxx>
---
net/core/bpf_sk_storage.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c
index d4172534dfa8..6f1afbb394a6 100644
--- a/net/core/bpf_sk_storage.c
+++ b/net/core/bpf_sk_storage.c
@@ -511,6 +511,11 @@ bpf_sk_storage_diag_alloc(const struct nlattr *nla_stgs)
if (nla_type(nla) != SK_DIAG_BPF_STORAGE_REQ_MAP_FD)
continue;
+ if (nla_len(nla) < sizeof(map_fd)) {
+ err = -EINVAL;
+ goto err_free;
+ }
+
map_fd = nla_get_u32(nla);
map = bpf_map_get(map_fd);
if (IS_ERR(map)) {
--
2.17.1
