[PATCH net] nfc: avoid potential race condition
From: Dan Carpenter <hidden>
Date: 2021-09-23 06:51:41
Also in:
kernel-janitors
Subsystem:
networking [general], nfc subsystem, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Heidelberg, Linus Torvalds
This from static analysis inspired by CVE-2021-26708 where there was a
race condition because it didn't lock_sock(sk) before saving
"vsk->transport". Here it is saving "llcp_sock->local" but the concept
is the same that it needs to take the lock first.
Fixes: 00e856db49bb ("NFC: llcp: Fall back to local values when getting socket options")
Fixes: d646960f7986 ("NFC: Initial LLCP support")
Signed-off-by: Dan Carpenter <redacted>
---
net/nfc/llcp_sock.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
index 6cfd30fc0798..74f4209c7144 100644
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c@@ -314,14 +314,16 @@ static int nfc_llcp_getsockopt(struct socket *sock, int level, int optname, if (get_user(len, optlen)) return -EFAULT; - local = llcp_sock->local; - if (!local) - return -ENODEV; - len = min_t(u32, len, sizeof(u32)); lock_sock(sk); + local = llcp_sock->local; + if (!local) { + release_sock(sk); + return -ENODEV; + } + switch (optname) { case NFC_LLCP_RW: rw = llcp_sock->rw > LLCP_MAX_RW ? local->rw : llcp_sock->rw;
@@ -598,14 +600,15 @@ static int llcp_sock_release(struct socket *sock) pr_debug("%p\n", sk); + lock_sock(sk); + local = llcp_sock->local; if (local == NULL) { + release_sock(sk); err = -ENODEV; goto out; } - lock_sock(sk); - /* Send a DISC */ if (sk->sk_state == LLCP_CONNECTED) nfc_llcp_send_disconnect(llcp_sock);
--
2.20.1