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| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2018-07-18 18:57:27 +0900 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-07-18 10:51:45 -0700 |
| commit | 3bc53be9db21040b5d2de4d455f023c8c494aa68 (patch) | |
| tree | aca5ff34b83771aabde98a6d5e31bca8e6769977 /net/nfc | |
| parent | 83ed7d1fe2d2d4a11b30660dec20168bb473d9c1 (diff) | |
| download | lwn-3bc53be9db21040b5d2de4d455f023c8c494aa68.tar.gz lwn-3bc53be9db21040b5d2de4d455f023c8c494aa68.zip | |
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>
Diffstat (limited to 'net/nfc')
| -rw-r--r-- | net/nfc/llcp_commands.c | 9 |
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); |