NFC: llcp: Limit size of SDP URI

[ Upstream commit fe9c842695e26d8116b61b80bfb905356f07834b ]

The tlv_len is u8, so we need to limit the size of the SDP URI. Enforce
this both in the NLA policy and in the code that performs the allocation
and copy, to avoid writing past the end of the allocated buffer.

Fixes: d9b8d8e19b073 ("NFC: llcp: Service Name Lookup netlink interface")
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/nfc/llcp_commands.c b/net/nfc/llcp_commands.c
index 367d8c02710181f06bf1a422e41239ed12e77d90..2ceefa183ceed6ba3d06f2aae958104a514f2146 100644 (file)
--- a/net/nfc/llcp_commands.c
+++ b/net/nfc/llcp_commands.c
@@ -149,6 +149,10 @@ struct nfc_llcp_sdp_tlv *nfc_llcp_build_sdreq_tlv(u8 tid, char *uri,
 
        pr_debug("uri: %s, len: %zu\n", uri, uri_len);
 
+       /* sdreq->tlv_len is u8, takes uri_len, + 3 for header, + 1 for NULL */
+       if (WARN_ON_ONCE(uri_len > U8_MAX - 4))
+               return NULL;
+
        sdreq = kzalloc(sizeof(struct nfc_llcp_sdp_tlv), GFP_KERNEL);
        if (sdreq == NULL)
                return NULL;

diff --git a/net/nfc/netlink.c b/net/nfc/netlink.c
index b251fb936a27a9632c55d5aa91c1dbd2fa543ffa..08ed6abe4aaedc2c2854902fd3caf60974b8b287 100644 (file)
--- a/net/nfc/netlink.c
+++ b/net/nfc/netlink.c
@@ -61,7 +61,8 @@ static const struct nla_policy nfc_genl_policy[NFC_ATTR_MAX + 1] = {
 };
 
 static const struct nla_policy nfc_sdp_genl_policy[NFC_SDP_ATTR_MAX + 1] = {
-       [NFC_SDP_ATTR_URI] = { .type = NLA_STRING },
+       [NFC_SDP_ATTR_URI] = { .type = NLA_STRING,
+                              .len = U8_MAX - 4 },
        [NFC_SDP_ATTR_SAP] = { .type = NLA_U8 },
 };