On Feb 1, 2021, at 12:32 PM, Sabyrzhan Tasbolatov <snovitoll@xxxxxxxxx> wrote: > > 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> > — Looks fine by me. Acked-by: Santosh Shilimkar <santosh.shilimkar@xxxxxxxxxx>
