From 6bf6ca7515c1df06f5c03737537f5e0eb191e29e Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Thu, 20 Nov 2014 20:50:07 -0800 Subject: [PATCH] iscsi-target: Fail connection on short sendmsg writes This patch changes iscsit_do_tx_data() to fail on short writes when kernel_sendmsg() returns a value different than requested transfer length, returning -EPIPE and thus causing a connection reset to occur. This avoids a potential bug in the original code where a short write would result in kernel_sendmsg() being called again with the original iovec base + length. In practice this has not been an issue because iscsit_do_tx_data() is only used for transferring 48 byte headers + 4 byte digests, along with seldom used control payloads from NOPIN + TEXT_RSP + REJECT with less than 32k of data. So following Al's audit of iovec consumers, go ahead and fail the connection on short writes for now, and remove the bogus logic ahead of his proper upstream fix. Reported-by: Al Viro Cc: David S. Miller Cc: # v3.1+ Signed-off-by: Nicholas Bellinger --- drivers/target/iscsi/iscsi_target_util.c | 26 ++++++++++-------------- 1 file changed, 11 insertions(+), 15 deletions(-) diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c index ce87ce9bdb9c..0b68c2ebce95 100644 --- a/drivers/target/iscsi/iscsi_target_util.c +++ b/drivers/target/iscsi/iscsi_target_util.c @@ -1358,15 +1358,15 @@ static int iscsit_do_tx_data( struct iscsi_conn *conn, struct iscsi_data_count *count) { - int data = count->data_length, total_tx = 0, tx_loop = 0, iov_len; + int ret, iov_len; struct kvec *iov_p; struct msghdr msg; if (!conn || !conn->sock || !conn->conn_ops) return -1; - if (data <= 0) { - pr_err("Data length is: %d\n", data); + if (count->data_length <= 0) { + pr_err("Data length is: %d\n", count->data_length); return -1; } @@ -1375,20 +1375,16 @@ static int iscsit_do_tx_data( iov_p = count->iov; iov_len = count->iov_count; - while (total_tx < data) { - tx_loop = kernel_sendmsg(conn->sock, &msg, iov_p, iov_len, - (data - total_tx)); - if (tx_loop <= 0) { - pr_debug("tx_loop: %d total_tx %d\n", - tx_loop, total_tx); - return tx_loop; - } - total_tx += tx_loop; - pr_debug("tx_loop: %d, total_tx: %d, data: %d\n", - tx_loop, total_tx, data); + ret = kernel_sendmsg(conn->sock, &msg, iov_p, iov_len, + count->data_length); + if (ret != count->data_length) { + pr_err("Unexpected ret: %d send data %d\n", + ret, count->data_length); + return -EPIPE; } + pr_debug("ret: %d, sent data: %d\n", ret, count->data_length); - return total_tx; + return ret; } int rx_data( -- 2.34.1