| Message ID | 0d8847df2f13e0831ee2f5504d06d5d12036d8f9.1703126594.git.nabijaczleweli@nabijaczleweli.xyz (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Avoid unprivileged splice(file->)/(->socket) pipe exclusion | expand |
diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c index 65d1f6755f98..ccfc46f31891 100644 --- a/net/kcm/kcmsock.c +++ b/net/kcm/kcmsock.c @@ -1028,7 +1028,7 @@ static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos, /* Only support splice for SOCKSEQPACKET */ - skb = skb_recv_datagram(sk, flags, &err); + skb = skb_recv_datagram(sk, MSG_DONTWAIT, &err); if (!skb) goto err_out;
Otherwise we risk sleeping with the pipe locked for indeterminate lengths of time ‒ given: cat > kcm.c <<^D #define _GNU_SOURCE #include <fcntl.h> #include <sys/socket.h> #include <netinet/in.h> #include <linux/kcm.h> int main() { int kcm = socket(AF_KCM, SOCK_SEQPACKET, KCMPROTO_CONNECTED); for (;;) splice(kcm, 0, 1, 0, 128 * 1024 * 1024, 0); } ^D cc kcm.c -o kcm mkfifo fifo ./kcm > fifo & read -r _ < fifo & sleep 0.1 echo zupa > fifo kcm used to sleep in splice and the shell used to enter an uninterruptible sleep in open("fifo"); now the splice returns -EAGAIN and the whole program completes. Also: don't pass the SPLICE_F_*-style flags argument to skb_recv_datagram(), which expects MSG_*-style flags. This fixes SPLICE_F_NONBLOCK not having worked. Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> --- net/kcm/kcmsock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)