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NFC: llcp: Limit size of SDP URI 

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: d9b8d8e19b ("NFC: llcp: Service Name Lookup netlink interface")
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kees Cook 2018-02-14 15:45:07 -08:00 committed by David S. Miller
parent c410c1966f
commit fe9c842695
2 changed files with 6 additions and 1 deletions
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4
net/nfc/llcp_commands.c
View File

@ -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;

3
net/nfc/netlink.c
View File

@ -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 },
};