From c9aa81faf19115fc2e732e7f210b37bb316987ff Mon Sep 17 00:00:00 2001 From: Tuong Lien Date: Thu, 11 Jun 2020 17:07:35 +0700 Subject: tipc: fix kernel WARNING in tipc_msg_append() syzbot found the following issue: WARNING: CPU: 0 PID: 6808 at include/linux/thread_info.h:150 check_copy_size include/linux/thread_info.h:150 [inline] WARNING: CPU: 0 PID: 6808 at include/linux/thread_info.h:150 copy_from_iter include/linux/uio.h:144 [inline] WARNING: CPU: 0 PID: 6808 at include/linux/thread_info.h:150 tipc_msg_append+0x49a/0x5e0 net/tipc/msg.c:242 Kernel panic - not syncing: panic_on_warn set ... This happens after commit 5e9eeccc58f3 ("tipc: fix NULL pointer dereference in streaming") that tried to build at least one buffer even when the message data length is zero... However, it now exposes another bug that the 'mss' can be zero and the 'cpy' will be negative, thus the above kernel WARNING will appear! The zero value of 'mss' is never expected because it means Nagle is not enabled for the socket (actually the socket type was 'SOCK_SEQPACKET'), so the function 'tipc_msg_append()' must not be called at all. But that was in this particular case since the message data length was zero, and the 'send <= maxnagle' check became true. We resolve the issue by explicitly checking if Nagle is enabled for the socket, i.e. 'maxnagle != 0' before calling the 'tipc_msg_append()'. We also reinforce the function to against such a negative values if any. Reported-by: syzbot+75139a7d2605236b0b7f@syzkaller.appspotmail.com Fixes: c0bceb97db9e ("tipc: add smart nagle feature") Acked-by: Jon Maloy Signed-off-by: Tuong Lien Signed-off-by: David S. Miller --- net/tipc/msg.c | 4 ++-- net/tipc/socket.c | 3 ++- 2 files changed, 4 insertions(+), 3 deletions(-) (limited to 'net/tipc') diff --git a/net/tipc/msg.c b/net/tipc/msg.c index 046e4cb3acea..01b64869a173 100644 --- a/net/tipc/msg.c +++ b/net/tipc/msg.c @@ -238,14 +238,14 @@ int tipc_msg_append(struct tipc_msg *_hdr, struct msghdr *m, int dlen, hdr = buf_msg(skb); curr = msg_blocks(hdr); mlen = msg_size(hdr); - cpy = min_t(int, rem, mss - mlen); + cpy = min_t(size_t, rem, mss - mlen); if (cpy != copy_from_iter(skb->data + mlen, cpy, &m->msg_iter)) return -EFAULT; msg_set_size(hdr, mlen + cpy); skb_put(skb, cpy); rem -= cpy; total += msg_blocks(hdr) - curr; - } while (rem); + } while (rem > 0); return total - accounted; } diff --git a/net/tipc/socket.c b/net/tipc/socket.c index 26123f4177fd..a94f38333698 100644 --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -1574,7 +1574,8 @@ static int __tipc_sendstream(struct socket *sock, struct msghdr *m, size_t dlen) break; send = min_t(size_t, dlen - sent, TIPC_MAX_USER_MSG_SIZE); blocks = tsk->snd_backlog; - if (tsk->oneway++ >= tsk->nagle_start && send <= maxnagle) { + if (tsk->oneway++ >= tsk->nagle_start && maxnagle && + send <= maxnagle) { rc = tipc_msg_append(hdr, m, send, maxnagle, txq); if (unlikely(rc < 0)) break; -- cgit v1.2.3 From 9798278260e8f61d04415342544a8f701bc5ace7 Mon Sep 17 00:00:00 2001 From: Tuong Lien Date: Thu, 11 Jun 2020 17:08:08 +0700 Subject: tipc: fix NULL pointer dereference in tipc_disc_rcv() When a bearer is enabled, we create a 'tipc_discoverer' object to store the bearer related data along with a timer and a preformatted discovery message buffer for later probing... However, this is only carried after the bearer was set 'up', that left a race condition resulting in kernel panic. It occurs when a discovery message from a peer node is received and processed in bottom half (since the bearer is 'up' already) just before the discoverer object is created but is now accessed in order to update the preformatted buffer (with a new trial address, ...) so leads to the NULL pointer dereference. We solve the problem by simply moving the bearer 'up' setting to later, so make sure everything is ready prior to any message receiving. Acked-by: Jon Maloy Signed-off-by: Tuong Lien Signed-off-by: David S. Miller --- net/tipc/bearer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/tipc') diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c index 34ca7b789eba..e366ec9a7e4d 100644 --- a/net/tipc/bearer.c +++ b/net/tipc/bearer.c @@ -316,7 +316,6 @@ static int tipc_enable_bearer(struct net *net, const char *name, b->domain = disc_domain; b->net_plane = bearer_id + 'A'; b->priority = prio; - test_and_set_bit_lock(0, &b->up); refcount_set(&b->refcnt, 1); res = tipc_disc_create(net, b, &b->bcast_addr, &skb); @@ -326,6 +325,7 @@ static int tipc_enable_bearer(struct net *net, const char *name, goto rejected; } + test_and_set_bit_lock(0, &b->up); rcu_assign_pointer(tn->bearer_list[bearer_id], b); if (skb) tipc_bearer_xmit_skb(net, bearer_id, skb, &b->bcast_addr); -- cgit v1.2.3