From: shamir rabinovitch <shamir.rabinovitch@xxxxxxxxxx> 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." Suggested-by: Leon Romanovsky <leon@xxxxxxxxxx> Acked-by: Santosh Shilimkar <santosh.shilimkar@xxxxxxxxxx> Signed-off-by: shamir rabinovitch <shamir.rabinovitch@xxxxxxxxxx> --- net/rds/message.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/net/rds/message.c b/net/rds/message.c index 4b00b1152a5f..c28ad4b111af 100644 --- a/net/rds/message.c +++ b/net/rds/message.c @@ -313,11 +313,14 @@ struct scatterlist *rds_message_alloc_sgs(struct rds_message *rm, int nents) 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 (rm->m_used_sgs + nents > rm->m_total_sgs) + 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); return NULL; + } + + if (!nents) + pr_warn("rds: alloc sgs failed! nents 0\n"); sg_ret = &sg_first[rm->m_used_sgs]; sg_init_table(sg_ret, nents); -- 2.19.1
