From c75ab8a55ac1083c232e4407f52b0cadae6c1e0e Mon Sep 17 00:00:00 2001 From: shamir rabinovitch Date: Sun, 16 Dec 2018 09:01:09 +0200 Subject: 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: Leon Romanovsky Acked-by: Santosh Shilimkar Signed-off-by: shamir rabinovitch Signed-off-by: David S. Miller --- net/rds/message.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) (limited to 'net/rds/message.c') diff --git a/net/rds/message.c b/net/rds/message.c index 4b00b1152a5f..f139420ba1f6 100644 --- a/net/rds/message.c +++ b/net/rds/message.c @@ -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) { -- cgit v1.2.3