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Commit 6e51fe75 authored by Tommi Rantala's avatar Tommi Rantala Committed by David S. Miller
Browse files

sctp: fix -ENOMEM result with invalid user space pointer in sendto() syscall 



Consider the following program, that sets the second argument to the
sendto() syscall incorrectly:

 #include <string.h>
 #include <arpa/inet.h>
 #include <sys/socket.h>

 int main(void)
 {
         int fd;
         struct sockaddr_in sa;

         fd = socket(AF_INET, SOCK_STREAM, 132 /*IPPROTO_SCTP*/);
         if (fd < 0)
                 return 1;

         memset(&sa, 0, sizeof(sa));
         sa.sin_family = AF_INET;
         sa.sin_addr.s_addr = inet_addr("127.0.0.1");
         sa.sin_port = htons(11111);

         sendto(fd, NULL, 1, 0, (struct sockaddr *)&sa, sizeof(sa));

         return 0;
 }

We get -ENOMEM:

 $ strace -e sendto ./demo
 sendto(3, NULL, 1, 0, {sa_family=AF_INET, sin_port=htons(11111), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 ENOMEM (Cannot allocate memory)

Propagate the error code from sctp_user_addto_chunk(), so that we will
tell user space what actually went wrong:

 $ strace -e sendto ./demo
 sendto(3, NULL, 1, 0, {sa_family=AF_INET, sin_port=htons(11111), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 EFAULT (Bad address)

Noticed while running Trinity (the syscall fuzzer).

Signed-off-by: default avatarTommi Rantala <tt.rantala@gmail.com>
Acked-by: default avatarVlad Yasevich <vyasevich@gmail.com>
Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent be364c8c

net/sctp/chunk.c

+9 −4
Original line number Original line Diff line number Diff line
@@ -183,7 +183,7 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc, 




	msg = sctp_datamsg_new(GFP_KERNEL);

	msg = sctp_datamsg_new(GFP_KERNEL);

	if (!msg)

	if (!msg)

		return NULL;

		return ERR_PTR(-ENOMEM);





	/* Note: Calculate this outside of the loop, so that all fragments

	/* Note: Calculate this outside of the loop, so that all fragments

	 * have the same expiration.

	 * have the same expiration.
@@ -280,8 +280,11 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc, 




		chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0);

		chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0);





		if (!chunk)

		if (!chunk) {

			err = -ENOMEM;

			goto errout;

			goto errout;

		}



		err = sctp_user_addto_chunk(chunk, offset, len, msgh->msg_iov);

		err = sctp_user_addto_chunk(chunk, offset, len, msgh->msg_iov);

		if (err < 0)

		if (err < 0)

			goto errout_chunk_free;

			goto errout_chunk_free;
@@ -315,8 +318,10 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc, 




		chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);

		chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);





		if (!chunk)

		if (!chunk) {

			err = -ENOMEM;

			goto errout;

			goto errout;

		}





		err = sctp_user_addto_chunk(chunk, offset, over,msgh->msg_iov);

		err = sctp_user_addto_chunk(chunk, offset, over,msgh->msg_iov);
@@ -342,7 +347,7 @@ errout: 
		sctp_chunk_free(chunk);

		sctp_chunk_free(chunk);

	}

	}

	sctp_datamsg_put(msg);

	sctp_datamsg_put(msg);

	return NULL;

	return ERR_PTR(err);

}

}





/* Check whether this message has expired. */

/* Check whether this message has expired. */

net/sctp/socket.c

+2 −2
Original line number Original line Diff line number Diff line
@@ -1915,8 +1915,8 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk, 




	/* Break the message into multiple chunks of maximum size. */

	/* Break the message into multiple chunks of maximum size. */

	datamsg = sctp_datamsg_from_user(asoc, sinfo, msg, msg_len);

	datamsg = sctp_datamsg_from_user(asoc, sinfo, msg, msg_len);

	if (!datamsg) {

	if (IS_ERR(datamsg)) {

		err = -ENOMEM;

		err = PTR_ERR(datamsg);

		goto out_free;

		goto out_free;

	}

	}