Message ID | 20200525080400.13195-1-bjorn.topel@gmail.com |
---|---|
State | Accepted |
Delegated to: | BPF Maintainers |
Headers | show |
Series | [bpf] xsk: add overflow check for u64 division, stored into u32 | expand |
On Mon, May 25, 2020 at 10:03:59AM +0200, Björn Töpel wrote: > From: Björn Töpel <bjorn.topel@intel.com> > > 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. > > Link: https://lore.kernel.org/bpf/CACtPs=GGvV-_Yj6rbpzTVnopgi5nhMoCcTkSkYrJHGQHJWFZMQ@mail.gmail.com/ > 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> Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
On 5/25/20 10:03 AM, Björn Töpel wrote: > From: Björn Töpel <bjorn.topel@intel.com> > > 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. > > Link: https://lore.kernel.org/bpf/CACtPs=GGvV-_Yj6rbpzTVnopgi5nhMoCcTkSkYrJHGQHJWFZMQ@mail.gmail.com/ > 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> Applied, thanks!
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c index ed7a6060f73c..3889bd9aec46 100644 --- a/net/xdp/xdp_umem.c +++ b/net/xdp/xdp_umem.c @@ -341,8 +341,8 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) { bool unaligned_chunks = mr->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG; 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; if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) { @@ -372,6 +372,10 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) 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; @@ -391,7 +395,7 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) umem->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; umem->flags = mr->flags;