On Tue, Feb 11, 2025 at 6:22 AM Tariq Toukan <ttoukan.linux@xxxxxxxxx> wrote:
>
>
>
> On 11/02/2025 2:01, Justin Stitt wrote:
> > On Mon, Feb 10, 2025 at 09:45:05AM -0800, Kees Cook wrote:
> >> GCC can see that the value range for "order" is capped, but this leads
> >> it to consider that it might be negative, leading to a false positive
> >> warning (with GCC 15 with -Warray-bounds -fdiagnostics-details):
> >>
> >> ../drivers/net/ethernet/mellanox/mlx4/alloc.c:691:47: error: array subscript -1 is below array bounds of 'long unsigned int *[2]' [-Werror=array-bounds=]
> >> 691 | i = find_first_bit(pgdir->bits[o], MLX4_DB_PER_PAGE >> o);
> >> | ~~~~~~~~~~~^~~
> >> 'mlx4_alloc_db_from_pgdir': events 1-2
> >> 691 | i = find_first_bit(pgdir->bits[o], MLX4_DB_PER_PAGE >> o); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> | | | | | (2) out of array bounds here
> >> | (1) when the condition is evaluated to true In file included from ../drivers/net/ethernet/mellanox/mlx4/mlx4.h:53,
> >> from ../drivers/net/ethernet/mellanox/mlx4/alloc.c:42:
> >> ../include/linux/mlx4/device.h:664:33: note: while referencing 'bits'
> >> 664 | unsigned long *bits[2];
> >> | ^~~~
> >>
> >> Switch the argument to unsigned int, which removes the compiler needing
> >> to consider negative values.
> >>
> >> Signed-off-by: Kees Cook <kees@xxxxxxxxxx>
> >> ---
> >> Cc: Tariq Toukan <tariqt@xxxxxxxxxx>
> >> Cc: Andrew Lunn <andrew+netdev@xxxxxxx>
> >> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> >> Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
> >> Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
> >> Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
> >> Cc: Yishai Hadas <yishaih@xxxxxxxxxx>
> >> Cc: netdev@xxxxxxxxxxxxxxx
> >> Cc: linux-rdma@xxxxxxxxxxxxxxx
> >> ---
> >> drivers/net/ethernet/mellanox/mlx4/alloc.c | 6 +++---
> >> include/linux/mlx4/device.h | 2 +-
> >> 2 files changed, 4 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/net/ethernet/mellanox/mlx4/alloc.c b/drivers/net/ethernet/mellanox/mlx4/alloc.c
> >> index b330020dc0d6..f2bded847e61 100644
> >> --- a/drivers/net/ethernet/mellanox/mlx4/alloc.c
> >> +++ b/drivers/net/ethernet/mellanox/mlx4/alloc.c
> >> @@ -682,9 +682,9 @@ static struct mlx4_db_pgdir *mlx4_alloc_db_pgdir(struct device *dma_device)
> >> }
> >>
> >> static int mlx4_alloc_db_from_pgdir(struct mlx4_db_pgdir *pgdir,
> >> - struct mlx4_db *db, int order)
> >> + struct mlx4_db *db, unsigned int order)
> >> {
> >> - int o;
> >> + unsigned int o;
> >> int i;
> >>
> >> for (o = order; o <= 1; ++o) {
> >
> > ^ Knowing now that @order can only be 0 or 1 can this for loop (and
> > goto) be dropped entirely?
> >
>
> Maybe I'm missing something...
> Can you please explain why you think this can be dropped?
I meant "rewritten to use two if statements" instead of "dropped". I
think "replaced" or "refactored" was the word I wanted.
>
>
> > The code is already short and sweet so I don't feel strongly either
> > way.
> >
> >> @@ -712,7 +712,7 @@ static int mlx4_alloc_db_from_pgdir(struct mlx4_db_pgdir *pgdir,
> >> return 0;
> >> }
> >>
> >> -int mlx4_db_alloc(struct mlx4_dev *dev, struct mlx4_db *db, int order)
> >> +int mlx4_db_alloc(struct mlx4_dev *dev, struct mlx4_db *db, unsigned int order)
> >> {
> >> struct mlx4_priv *priv = mlx4_priv(dev);
> >> struct mlx4_db_pgdir *pgdir;
> >> diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h
> >> index 27f42f713c89..86f0f2a25a3d 100644
> >> --- a/include/linux/mlx4/device.h
> >> +++ b/include/linux/mlx4/device.h
> >> @@ -1135,7 +1135,7 @@ int mlx4_write_mtt(struct mlx4_dev *dev, struct mlx4_mtt *mtt,
> >> int mlx4_buf_write_mtt(struct mlx4_dev *dev, struct mlx4_mtt *mtt,
> >> struct mlx4_buf *buf);
> >>
> >> -int mlx4_db_alloc(struct mlx4_dev *dev, struct mlx4_db *db, int order);
> >> +int mlx4_db_alloc(struct mlx4_dev *dev, struct mlx4_db *db, unsigned int order);
> >> void mlx4_db_free(struct mlx4_dev *dev, struct mlx4_db *db);
> >>
> >> int mlx4_alloc_hwq_res(struct mlx4_dev *dev, struct mlx4_hwq_resources *wqres,
> >> --
> >> 2.34.1
> >>
> >
> > Justin
> >
>
