| Message ID | 20210905155728.11147-1-len.baker@gmx.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | serial: 8250_pci: Prefer struct_size over open coded arithmetic | expand |
On Sun, Sep 5, 2021 at 6:58 PM 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 + size * count" in the kzalloc() function. Makes sense Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> > [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/tty/serial/8250/8250_pci.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c > index a808c283883e..b97ade35d4a3 100644 > --- a/drivers/tty/serial/8250/8250_pci.c > +++ b/drivers/tty/serial/8250/8250_pci.c > @@ -3981,9 +3981,7 @@ pciserial_init_ports(struct pci_dev *dev, const struct pciserial_board *board) > nr_ports = rc; > } > > - priv = kzalloc(sizeof(struct serial_private) + > - sizeof(unsigned int) * nr_ports, > - GFP_KERNEL); > + priv = kzalloc(struct_size(priv, line, nr_ports), GFP_KERNEL); > if (!priv) { > priv = ERR_PTR(-ENOMEM); > goto err_deinit; > -- > 2.25.1 >
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c index a808c283883e..b97ade35d4a3 100644 --- a/drivers/tty/serial/8250/8250_pci.c +++ b/drivers/tty/serial/8250/8250_pci.c @@ -3981,9 +3981,7 @@ pciserial_init_ports(struct pci_dev *dev, const struct pciserial_board *board) nr_ports = rc; } - priv = kzalloc(sizeof(struct serial_private) + - sizeof(unsigned int) * nr_ports, - GFP_KERNEL); + priv = kzalloc(struct_size(priv, line, nr_ports), GFP_KERNEL); if (!priv) { priv = ERR_PTR(-ENOMEM); goto err_deinit;
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 + size * count" 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/tty/serial/8250/8250_pci.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) -- 2.25.1