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| author | Björn Töpel <bjorn.topel@intel.com> | 2020-05-25 10:03:59 +0200 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2020-05-26 00:06:00 +0200 |
| commit | b16a87d0aef7a6be766f6618976dc5ff2c689291 (patch) | |
| tree | f11fe5d40a3ad84d2fa05b301c0484282f9dbe40 /net/xdp | |
| parent | d04322a0da1e86aedaa322ce933cfb8c0191d1eb (diff) | |
| download | lwn-b16a87d0aef7a6be766f6618976dc5ff2c689291.tar.gz lwn-b16a87d0aef7a6be766f6618976dc5ff2c689291.zip | |
xsk: Add overflow check for u64 division, stored into u32
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-_Yj6rbpzTVnopgi5nhMoCcTkSkYrJHGQHJWFZMQ@mail.gmail.com/
Link: https://lore.kernel.org/bpf/20200525080400.13195-1-bjorn.topel@gmail.com
Diffstat (limited to 'net/xdp')
| -rw-r--r-- | net/xdp/xdp_umem.c | 8 |
1 files changed, 6 insertions, 2 deletions
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; |