From 1357bab4b26d0ca4efc56d46ff9a94caacd8510b Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 14 Feb 2018 15:45:07 -0800 Subject: [PATCH] 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: f6b990c3c8eaf ("NFC: llcp: Service Name Lookup netlink interface") Signed-off-by: Kees Cook Signed-off-by: David S. Miller --- net/nfc/llcp_commands.c | 4 ++++ net/nfc/netlink.c | 3 ++- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/net/nfc/llcp_commands.c b/net/nfc/llcp_commands.c index 367d8c0271018..2ceefa183ceed 100644 --- 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 c0b83dc9d9930..f018eafc2a0de 100644 --- 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 }, }; -- 2.39.5