From fe9c842695e26d8116b61b80bfb905356f07834b Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Wed, 14 Feb 2018 15:45:07 -0800
Subject: [PATCH] NFC: llcp: Limit size of SDP URI
Git-commit: fe9c842695e26d8116b61b80bfb905356f07834b
Patch-mainline: v4.16-rc3
References: bsc#1051510
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>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
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 367d8c027101..2ceefa183cee 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 c0b83dc9d993..f018eafc2a0d 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 },
};
--
2.18.0