xsk: Fix unaligned descriptor validation

Make sure unaligned descriptors that straddle the end of the UMEM are
considered invalid. Currently, descriptor validation is broken for
zero-copy mode which only checks descriptors at page granularity.
For example, descriptors in zero-copy mode that overrun the end of the
UMEM but not a page boundary are (incorrectly) considered valid. The
UMEM boundary check needs to happen before the page boundary and
contiguity checks in xp_desc_crosses_non_contig_pg(). Do this check in
xp_unaligned_validate_desc() instead like xp_check_unaligned() already
does.

Fixes: 2b43470add8c ("xsk: Introduce AF_XDP buffer allocation API")
Signed-off-by: Kal Conley <kal.conley@dectris.com>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/r/20230405235920.7305-2-kal.conley@dectris.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
index 3e952e5..d318c76 100644 (file)
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h
@@ -180,13 +180,8 @@ static inline bool xp_desc_crosses_non_contig_pg(struct xsk_buff_pool *pool,
        if (likely(!cross_pg))
                return false;
 
-       if (pool->dma_pages_cnt) {
-               return !(pool->dma_pages[addr >> PAGE_SHIFT] &
-                        XSK_NEXT_PG_CONTIG_MASK);
-       }
-
-       /* skb path */
-       return addr + len > pool->addrs_cnt;
+       return pool->dma_pages_cnt &&
+              !(pool->dma_pages[addr >> PAGE_SHIFT] & XSK_NEXT_PG_CONTIG_MASK);
 }
 
 static inline u64 xp_aligned_extract_addr(struct xsk_buff_pool *pool, u64 addr)

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index bfb2a7e..66c6f57 100644 (file)
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -162,6 +162,7 @@ static inline bool xp_unaligned_validate_desc(struct xsk_buff_pool *pool,
                return false;
 
        if (base_addr >= pool->addrs_cnt || addr >= pool->addrs_cnt ||
+           addr + desc->len > pool->addrs_cnt ||
            xp_desc_crosses_non_contig_pg(pool, addr, desc->len))
                return false;