4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ Upstream commit 31c07dffafce914c1d1543c135382a11ff058d93 ]
Sili Luo reported a race in nfc_llcp_sock_get(), leading to UAF.
Getting a reference on the socket found in a lookup while holding a lock should happen before releasing the lock.
nfc_llcp_sock_get_sn() has a similar problem.
Finally nfc_llcp_recv_snl() needs to make sure the socket found by nfc_llcp_sock_from_sn() does not disappear.
Fixes: 8f50020ed9b8 ("NFC: LLCP late binding") Reported-by: Sili Luo rootlab@huawei.com Signed-off-by: Eric Dumazet edumazet@google.com Cc: Willy Tarreau w@1wt.eu Reviewed-by: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org Link: https://lore.kernel.org/r/20231009123110.3735515-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/nfc/llcp_core.c | 30 ++++++++++++------------------ 1 file changed, 12 insertions(+), 18 deletions(-)
diff --git a/net/nfc/llcp_core.c b/net/nfc/llcp_core.c index bdc1a9d0965af..c30b28465e644 100644 --- a/net/nfc/llcp_core.c +++ b/net/nfc/llcp_core.c @@ -216,17 +216,13 @@ static struct nfc_llcp_sock *nfc_llcp_sock_get(struct nfc_llcp_local *local,
if (tmp_sock->ssap == ssap && tmp_sock->dsap == dsap) { llcp_sock = tmp_sock; + sock_hold(&llcp_sock->sk); break; } }
read_unlock(&local->sockets.lock);
- if (llcp_sock == NULL) - return NULL; - - sock_hold(&llcp_sock->sk); - return llcp_sock; }
@@ -338,7 +334,8 @@ static int nfc_llcp_wks_sap(const char *service_name, size_t service_name_len)
static struct nfc_llcp_sock *nfc_llcp_sock_from_sn(struct nfc_llcp_local *local, - const u8 *sn, size_t sn_len) + const u8 *sn, size_t sn_len, + bool needref) { struct sock *sk; struct nfc_llcp_sock *llcp_sock, *tmp_sock; @@ -374,6 +371,8 @@ struct nfc_llcp_sock *nfc_llcp_sock_from_sn(struct nfc_llcp_local *local,
if (memcmp(sn, tmp_sock->service_name, sn_len) == 0) { llcp_sock = tmp_sock; + if (needref) + sock_hold(&llcp_sock->sk); break; } } @@ -415,7 +414,8 @@ u8 nfc_llcp_get_sdp_ssap(struct nfc_llcp_local *local, * to this service name. */ if (nfc_llcp_sock_from_sn(local, sock->service_name, - sock->service_name_len) != NULL) { + sock->service_name_len, + false) != NULL) { mutex_unlock(&local->sdp_lock);
return LLCP_SAP_MAX; @@ -816,16 +816,7 @@ static struct nfc_llcp_sock *nfc_llcp_connecting_sock_get(struct nfc_llcp_local static struct nfc_llcp_sock *nfc_llcp_sock_get_sn(struct nfc_llcp_local *local, const u8 *sn, size_t sn_len) { - struct nfc_llcp_sock *llcp_sock; - - llcp_sock = nfc_llcp_sock_from_sn(local, sn, sn_len); - - if (llcp_sock == NULL) - return NULL; - - sock_hold(&llcp_sock->sk); - - return llcp_sock; + return nfc_llcp_sock_from_sn(local, sn, sn_len, true); }
static const u8 *nfc_llcp_connect_sn(const struct sk_buff *skb, size_t *sn_len) @@ -1290,7 +1281,8 @@ static void nfc_llcp_recv_snl(struct nfc_llcp_local *local, }
llcp_sock = nfc_llcp_sock_from_sn(local, service_name, - service_name_len); + service_name_len, + true); if (!llcp_sock) { sap = 0; goto add_snl; @@ -1310,6 +1302,7 @@ static void nfc_llcp_recv_snl(struct nfc_llcp_local *local,
if (sap == LLCP_SAP_MAX) { sap = 0; + nfc_llcp_sock_put(llcp_sock); goto add_snl; }
@@ -1327,6 +1320,7 @@ static void nfc_llcp_recv_snl(struct nfc_llcp_local *local,
pr_debug("%p %d\n", llcp_sock, sap);
+ nfc_llcp_sock_put(llcp_sock); add_snl: sdp = nfc_llcp_build_sdres_tlv(tid, sap); if (sdp == NULL)