xsk: Add missing overflow check in xdp_umem_reg

The number of chunks can overflow u32. Make sure to return -EINVAL on
overflow. Also remove a redundant u32 cast assigning umem->npgs.

Fixes: bbff2f321a86 ("xsk: new descriptor addressing scheme")
Signed-off-by: Kal Conley <kal.conley@dectris.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20230308174013.1114745-1-kal.conley@dectris.com

diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 4681e8e8ad943605b61aa6be685e6c76a70b4c0f..02207e852d796d31a04e3a1a83f500c27b21203d 100644 (file)
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -150,10 +150,11 @@ static int xdp_umem_account_pages(struct xdp_umem *umem)
 
 static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
 {
-       u32 npgs_rem, chunk_size = mr->chunk_size, headroom = mr->headroom;
        bool unaligned_chunks = mr->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG;
-       u64 npgs, addr = mr->addr, size = mr->len;
-       unsigned int chunks, chunks_rem;
+       u32 chunk_size = mr->chunk_size, headroom = mr->headroom;
+       u64 addr = mr->addr, size = mr->len;
+       u32 chunks_rem, npgs_rem;
+       u64 chunks, npgs;
        int err;
 
        if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) {
@@ -188,8 +189,8 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
        if (npgs > U32_MAX)
                return -EINVAL;
 
-       chunks = (unsigned int)div_u64_rem(size, chunk_size, &chunks_rem);
-       if (chunks == 0)
+       chunks = div_u64_rem(size, chunk_size, &chunks_rem);
+       if (!chunks || chunks > U32_MAX)
                return -EINVAL;
 
        if (!unaligned_chunks && chunks_rem)
@@ -202,7 +203,7 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
        umem->headroom = headroom;
        umem->chunk_size = chunk_size;
        umem->chunks = chunks;
-       umem->npgs = (u32)npgs;
+       umem->npgs = npgs;
        umem->pgs = NULL;
        umem->user = NULL;
        umem->flags = mr->flags;