From: Björn Töpel bjorn.topel@intel.com
commit b16a87d0aef7a6be766f6618976dc5ff2c689291 upstream.
The npgs member of struct xdp_umem is an u32 entity, and stores the number of pages the UMEM consumes. The calculation of npgs
npgs = size / PAGE_SIZE
can overflow.
To avoid overflow scenarios, the division is now first stored in a u64, and the result is verified to fit into 32b.
An alternative would be storing the npgs as a u64, however, this wastes memory and is an unrealisticly large packet area.
Fixes: c0c77d8fb787 ("xsk: add user memory registration support sockopt") Reported-by: "Minh Bùi Quang" minhquangbui99@gmail.com Signed-off-by: Björn Töpel bjorn.topel@intel.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Jonathan Lemon jonathan.lemon@gmail.com Link: https://lore.kernel.org/bpf/CACtPs=GGvV-_Yj6rbpzTVnopgi5nhMoCcTkSkYrJHGQHJWF... Link: https://lore.kernel.org/bpf/20200525080400.13195-1-bjorn.topel@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/xdp/xdp_umem.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- a/net/xdp/xdp_umem.c +++ b/net/xdp/xdp_umem.c @@ -258,8 +258,8 @@ static int xdp_umem_account_pages(struct static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) { u32 chunk_size = mr->chunk_size, headroom = mr->headroom; + u64 npgs, addr = mr->addr, size = mr->len; unsigned int chunks, chunks_per_page; - u64 addr = mr->addr, size = mr->len; int err, i;
if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) { @@ -285,6 +285,10 @@ static int xdp_umem_reg(struct xdp_umem if ((addr + size) < addr) return -EINVAL;
+ npgs = div_u64(size, PAGE_SIZE); + if (npgs > U32_MAX) + return -EINVAL; + chunks = (unsigned int)div_u64(size, chunk_size); if (chunks == 0) return -EINVAL; @@ -303,7 +307,7 @@ static int xdp_umem_reg(struct xdp_umem umem->props.size = size; umem->headroom = headroom; umem->chunk_size_nohr = chunk_size - headroom; - umem->npgs = size / PAGE_SIZE; + umem->npgs = (u32)npgs; umem->pgs = NULL; umem->user = NULL; INIT_LIST_HEAD(&umem->xsk_list);