| Message ID | 20210911131933.2089-1-len.baker@gmx.com |
|---|---|
| State | New |
| Headers | show |
| Series | memstick: jmb38x_ms: Prefer struct_size over open coded arithmetic | expand |
On Sat, 11 Sept 2021 at 15:22, Len Baker <len.baker@gmx.com> wrote: > > As noted in the "Deprecated Interfaces, Language Features, Attributes, > and Conventions" documentation [1], size calculations (especially > multiplication) should not be performed in memory allocator (or similar) > function arguments due to the risk of them overflowing. This could lead > to values wrapping around and a smaller allocation being made than the > caller was expecting. Using those allocations could lead to linear > overflows of heap memory and other misbehaviors. > > So, use the struct_size() helper to do the arithmetic instead of the > argument "size + count * size" in the kzalloc() function. > > [1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > > Signed-off-by: Len Baker <len.baker@gmx.com> Applied for next, thanks! Kind regards Uffe > --- > drivers/memstick/host/jmb38x_ms.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/memstick/host/jmb38x_ms.c b/drivers/memstick/host/jmb38x_ms.c > index f9a93b0565e1..a7a0f0caea15 100644 > --- a/drivers/memstick/host/jmb38x_ms.c > +++ b/drivers/memstick/host/jmb38x_ms.c > @@ -927,8 +927,7 @@ static int jmb38x_ms_probe(struct pci_dev *pdev, > goto err_out_int; > } > > - jm = kzalloc(sizeof(struct jmb38x_ms) > - + cnt * sizeof(struct memstick_host *), GFP_KERNEL); > + jm = kzalloc(struct_size(jm, hosts, cnt), GFP_KERNEL); > if (!jm) { > rc = -ENOMEM; > goto err_out_int; > -- > 2.25.1 >
diff --git a/drivers/memstick/host/jmb38x_ms.c b/drivers/memstick/host/jmb38x_ms.c index f9a93b0565e1..a7a0f0caea15 100644 --- a/drivers/memstick/host/jmb38x_ms.c +++ b/drivers/memstick/host/jmb38x_ms.c @@ -927,8 +927,7 @@ static int jmb38x_ms_probe(struct pci_dev *pdev, goto err_out_int; } - jm = kzalloc(sizeof(struct jmb38x_ms) - + cnt * sizeof(struct memstick_host *), GFP_KERNEL); + jm = kzalloc(struct_size(jm, hosts, cnt), GFP_KERNEL); if (!jm) { rc = -ENOMEM; goto err_out_int;
As noted in the "Deprecated Interfaces, Language Features, Attributes, and Conventions" documentation [1], size calculations (especially multiplication) should not be performed in memory allocator (or similar) function arguments due to the risk of them overflowing. This could lead to values wrapping around and a smaller allocation being made than the caller was expecting. Using those allocations could lead to linear overflows of heap memory and other misbehaviors. So, use the struct_size() helper to do the arithmetic instead of the argument "size + count * size" in the kzalloc() function. [1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments Signed-off-by: Len Baker <len.baker@gmx.com> --- drivers/memstick/host/jmb38x_ms.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) -- 2.25.1