2023-03-08 17:41:59

by Kal Cutter Conley

[permalink] [raw]
Subject: [PATCH bpf v3] 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 <[email protected]>
---
net/xdp/xdp_umem.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 4681e8e8ad94..02207e852d79 100644
--- 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;
--
2.39.2



2023-03-16 12:52:45

by Magnus Karlsson

[permalink] [raw]
Subject: Re: [PATCH bpf v3] xsk: Add missing overflow check in xdp_umem_reg

On Wed, 8 Mar 2023 at 18:51, Kal Conley <[email protected]> wrote:
>
> The number of chunks can overflow u32. Make sure to return -EINVAL on
> overflow.
>
> Also remove a redundant u32 cast assigning umem->npgs.

Thanks!

Acked-by: Magnus Karlsson <[email protected]>

> Fixes: bbff2f321a86 ("xsk: new descriptor addressing scheme")
> Signed-off-by: Kal Conley <[email protected]>
> ---
> net/xdp/xdp_umem.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
> index 4681e8e8ad94..02207e852d79 100644
> --- 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;
> --
> 2.39.2
>

2023-03-16 21:14:29

by Daniel Borkmann

[permalink] [raw]
Subject: Re: [PATCH bpf v3] xsk: Add missing overflow check in xdp_umem_reg

On 3/16/23 1:52 PM, Magnus Karlsson wrote:
> On Wed, 8 Mar 2023 at 18:51, Kal Conley <[email protected]> wrote:
>>
>> The number of chunks can overflow u32. Make sure to return -EINVAL on
>> overflow.
>>
>> Also remove a redundant u32 cast assigning umem->npgs.
>
> Thanks!
>
> Acked-by: Magnus Karlsson <[email protected]>
>
>> Fixes: bbff2f321a86 ("xsk: new descriptor addressing scheme")
>> Signed-off-by: Kal Conley <[email protected]>

Looks like patchbot was on partial strike, this was applied to bpf, thanks!