From: Sabyrzhan Tasbolatov <snovitoll@xxxxxxxxx> commit a11148e6fcce2ae53f47f0a442d098d860b4f7db upstream. 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> Acked-by: Santosh Shilimkar <santosh.shilimkar@xxxxxxxxxx> Link: https://lore.kernel.org/r/20210201203233.1324704-1-snovitoll@xxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/rds/rdma.c | 3 +++ 1 file changed, 3 insertions(+) --- a/net/rds/rdma.c +++ b/net/rds/rdma.c @@ -531,6 +531,9 @@ int rds_rdma_extra_size(struct rds_rdma_ 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);
