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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2018-07-18 18:57:27 +0900
committerDavid S. Miller <davem@davemloft.net>2018-07-18 10:51:45 -0700
commit3bc53be9db21040b5d2de4d455f023c8c494aa68 (patch)
treeaca5ff34b83771aabde98a6d5e31bca8e6769977
parent83ed7d1fe2d2d4a11b30660dec20168bb473d9c1 (diff)
net/nfc: Avoid stalls when nfc_alloc_send_skb() returned NULL.
syzbot is reporting stalls at nfc_llcp_send_ui_frame() [1]. This is because nfc_llcp_send_ui_frame() is retrying the loop without any delay when nonblocking nfc_alloc_send_skb() returned NULL. Since there is no need to use MSG_DONTWAIT if we retry until sock_alloc_send_pskb() succeeds, let's use blocking call. Also, in case an unexpected error occurred, let's break the loop if blocking nfc_alloc_send_skb() failed. [1] https://syzkaller.appspot.com/bug?id=4a131cc571c3733e0eff6bc673f4e36ae48f19c6 Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: syzbot <syzbot+d29d18215e477cfbfbdd@syzkaller.appspotmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/nfc/llcp_commands.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/net/nfc/llcp_commands.c b/net/nfc/llcp_commands.c
index 2ceefa183cee..6a196e438b6c 100644
--- a/net/nfc/llcp_commands.c
+++ b/net/nfc/llcp_commands.c
@@ -752,11 +752,14 @@ int nfc_llcp_send_ui_frame(struct nfc_llcp_sock *sock, u8 ssap, u8 dsap,
pr_debug("Fragment %zd bytes remaining %zd",
frag_len, remaining_len);
- pdu = nfc_alloc_send_skb(sock->dev, &sock->sk, MSG_DONTWAIT,
+ pdu = nfc_alloc_send_skb(sock->dev, &sock->sk, 0,
frag_len + LLCP_HEADER_SIZE, &err);
if (pdu == NULL) {
- pr_err("Could not allocate PDU\n");
- continue;
+ pr_err("Could not allocate PDU (error=%d)\n", err);
+ len -= remaining_len;
+ if (len == 0)
+ len = err;
+ break;
}
pdu = llcp_add_header(pdu, dsap, ssap, LLCP_PDU_UI);