Commit c75ab8a5 authored by shamir rabinovitch's avatar shamir rabinovitch Committed by David S. Miller
Browse files

net/rds: remove user triggered WARN_ON in rds_sendmsg 

per comment from Leon in rdma mailing list
https://lkml.org/lkml/2018/10/31/312 :

Please don't forget to remove user triggered WARN_ON.
https://lwn.net/Articles/769365/


"Greg Kroah-Hartman raised the problem of core kernel API code that will
use WARN_ON_ONCE() to complain about bad usage; that will not generate
the desired result if WARN_ON_ONCE() is configured to crash the machine.
He was told that the code should just call pr_warn() instead, and that
the called function should return an error in such situations. It was
generally agreed that any WARN_ON() or WARN_ON_ONCE() calls that can be
triggered from user space need to be fixed."

in addition harden rds_sendmsg to detect and overcome issues with
invalid sg count and fail the sendmsg.

Suggested-by: default avatarLeon Romanovsky <leon@kernel.org>
Acked-by: default avatarSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: default avatarshamir rabinovitch <shamir.rabinovitch@oracle.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ea010070

net/rds/message.c

+18 −6
Original line number Diff line number Diff line
@@ -308,16 +308,27 @@ out: 
/*

 * RDS ops use this to grab SG entries from the rm's sg pool.

 */

struct scatterlist *rds_message_alloc_sgs(struct rds_message *rm, int nents)

struct scatterlist *rds_message_alloc_sgs(struct rds_message *rm, int nents,

					  int *ret)

{

	struct scatterlist *sg_first = (struct scatterlist *) &rm[1];

	struct scatterlist *sg_ret;



	WARN_ON(rm->m_used_sgs + nents > rm->m_total_sgs);

	WARN_ON(!nents);

	if (WARN_ON(!ret))

		return NULL;



	if (rm->m_used_sgs + nents > rm->m_total_sgs)

	if (nents <= 0) {

		pr_warn("rds: alloc sgs failed! nents <= 0\n");

		*ret = -EINVAL;

		return NULL;

	}



	if (rm->m_used_sgs + nents > rm->m_total_sgs) {

		pr_warn("rds: alloc sgs failed! total %d used %d nents %d\n",

			rm->m_total_sgs, rm->m_used_sgs, nents);

		*ret = -ENOMEM;

		return NULL;

	}



	sg_ret = &sg_first[rm->m_used_sgs];

	sg_init_table(sg_ret, nents);
@@ -332,6 +343,7 @@ struct rds_message *rds_message_map_pages(unsigned long *page_addrs, unsigned in 
	unsigned int i;

	int num_sgs = ceil(total_len, PAGE_SIZE);

	int extra_bytes = num_sgs * sizeof(struct scatterlist);

	int ret;



	rm = rds_message_alloc(extra_bytes, GFP_NOWAIT);

	if (!rm)
@@ -340,10 +352,10 @@ struct rds_message *rds_message_map_pages(unsigned long *page_addrs, unsigned in 
	set_bit(RDS_MSG_PAGEVEC, &rm->m_flags);

	rm->m_inc.i_hdr.h_len = cpu_to_be32(total_len);

	rm->data.op_nents = ceil(total_len, PAGE_SIZE);

	rm->data.op_sg = rds_message_alloc_sgs(rm, num_sgs);

	rm->data.op_sg = rds_message_alloc_sgs(rm, num_sgs, &ret);

	if (!rm->data.op_sg) {

		rds_message_put(rm);

		return ERR_PTR(-ENOMEM);

		return ERR_PTR(ret);

	}



	for (i = 0; i < rm->data.op_nents; ++i) {

net/rds/rdma.c

+4 −8
Original line number Diff line number Diff line
@@ -623,11 +623,9 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm, 
	op->op_active = 1;

	op->op_recverr = rs->rs_recverr;

	WARN_ON(!nr_pages);

	op->op_sg = rds_message_alloc_sgs(rm, nr_pages);

	if (!op->op_sg) {

		ret = -ENOMEM;

	op->op_sg = rds_message_alloc_sgs(rm, nr_pages, &ret);

	if (!op->op_sg)

		goto out_pages;

	}



	if (op->op_notify || op->op_recverr) {

		/* We allocate an uninitialized notifier here, because
@@ -839,11 +837,9 @@ int rds_cmsg_atomic(struct rds_sock *rs, struct rds_message *rm, 
	rm->atomic.op_silent = !!(args->flags & RDS_RDMA_SILENT);

	rm->atomic.op_active = 1;

	rm->atomic.op_recverr = rs->rs_recverr;

	rm->atomic.op_sg = rds_message_alloc_sgs(rm, 1);

	if (!rm->atomic.op_sg) {

		ret = -ENOMEM;

	rm->atomic.op_sg = rds_message_alloc_sgs(rm, 1, &ret);

	if (!rm->atomic.op_sg)

		goto err;

	}



	/* verify 8 byte-aligned */

	if (args->local_addr & 0x7) {

net/rds/rds.h

+2 −1
Original line number Diff line number Diff line
@@ -839,7 +839,8 @@ rds_conn_connecting(struct rds_connection *conn) 


/* message.c */

struct rds_message *rds_message_alloc(unsigned int nents, gfp_t gfp);

struct scatterlist *rds_message_alloc_sgs(struct rds_message *rm, int nents);

struct scatterlist *rds_message_alloc_sgs(struct rds_message *rm, int nents,

					  int *ret);

int rds_message_copy_from_user(struct rds_message *rm, struct iov_iter *from,

			       bool zcopy);

struct rds_message *rds_message_map_pages(unsigned long *page_addrs, unsigned int total_len);

net/rds/send.c

+5 −4
Original line number Diff line number Diff line
@@ -886,6 +886,9 @@ static int rds_rm_size(struct msghdr *msg, int num_sgs, 
	bool zcopy_cookie = false;

	struct rds_iov_vector *iov, *tmp_iov;



	if (num_sgs < 0)

		return -EINVAL;



	for_each_cmsghdr(cmsg, msg) {

		if (!CMSG_OK(msg, cmsg))

			return -EINVAL;
@@ -1259,11 +1262,9 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len) 


	/* Attach data to the rm */

	if (payload_len) {

		rm->data.op_sg = rds_message_alloc_sgs(rm, num_sgs);

		if (!rm->data.op_sg) {

			ret = -ENOMEM;

		rm->data.op_sg = rds_message_alloc_sgs(rm, num_sgs, &ret);

		if (!rm->data.op_sg)

			goto out;

		}

		ret = rds_message_copy_from_user(rm, &msg->msg_iter, zcopy);

		if (ret)

			goto out;

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