syzbot found WARNING in rds_rdma_extra_size [1] when RDS_CMSG_RDMA_ARGS control message is passed with user-controlled 0x40001 bytes of args->nr_local, causing order >= MAX_ORDER condition. The exact value 0x40001 can be checked with UIO_MAXIOV which is 0x400. So for kcalloc() 0x400 iovecs with sizeof(struct rds_iovec) = 0x10 is the closest limit, with 0x10 leftover. Same condition is currently done in rds_cmsg_rdma_args(). [1] WARNING: mm/page_alloc.c:5011 [..] Call Trace: alloc_pages_current+0x18c/0x2a0 mm/mempolicy.c:2267 alloc_pages include/linux/gfp.h:547 [inline] kmalloc_order+0x2e/0xb0 mm/slab_common.c:837 kmalloc_order_trace+0x14/0x120 mm/slab_common.c:853 kmalloc_array include/linux/slab.h:592 [inline] kcalloc include/linux/slab.h:621 [inline] rds_rdma_extra_size+0xb2/0x3b0 net/rds/rdma.c:568 rds_rm_size net/rds/send.c:928 [inline] Reported-by: syzbot+1bd2b07f93745fa38425@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@xxxxxxxxx> --- net/rds/rdma.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/rds/rdma.c b/net/rds/rdma.c index 1d0afb1dd77b..6f1a50d50d06 100644 --- a/net/rds/rdma.c +++ b/net/rds/rdma.c @@ -565,6 +565,9 @@ int rds_rdma_extra_size(struct rds_rdma_args *args, if (args->nr_local == 0) return -EINVAL; + if (args->nr_local > UIO_MAXIOV) + return -EMSGSIZE; + iov->iov = kcalloc(args->nr_local, sizeof(struct rds_iovec), GFP_KERNEL); -- 2.25.1
