2019-09-07 08:35:59

by Arnd Bergmann

Subject: [PATCH] usnic: avoid overly large buffers on stack

It's never a good idea to put a 1000-byte buffer on the kernel
stack. The compiler warns about this instance when usnic_ib_log_vf()
gets inlined into usnic_ib_pci_probe():

drivers/infiniband/hw/usnic/usnic_ib_main.c:543:12: error: stack frame size of 1044 bytes in function 'usnic_ib_pci_probe' [-Werror,-Wframe-larger-than=]

As this is only called for debugging purposes in the setup path,
it's trivial to convert to a dynamic allocation.

Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/infiniband/hw/usnic/usnic_ib_main.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/usnic/usnic_ib_main.c b/drivers/infiniband/hw/usnic/usnic_ib_main.c
index 03f54eb9404b..c9abe1c01e4e 100644
--- a/drivers/infiniband/hw/usnic/usnic_ib_main.c
+++ b/drivers/infiniband/hw/usnic/usnic_ib_main.c
@@ -89,9 +89,15 @@ static void usnic_ib_dump_vf(struct usnic_ib_vf *vf, char *buf, int buf_sz)

void usnic_ib_log_vf(struct usnic_ib_vf *vf)
{
- char buf[1000];
- usnic_ib_dump_vf(vf, buf, sizeof(buf));
+ char *buf = kzalloc(1000, GFP_KERNEL);
+
+ if (!buf)
+ return;
+
+ usnic_ib_dump_vf(vf, buf, 1000);
usnic_dbg("%s\n", buf);
+
+ kfree(buf);
}

/* Start of netdev section */
--
2.20.0

2019-09-12 13:50:15

by Jason Gunthorpe

Subject: Re: [PATCH] usnic: avoid overly large buffers on stack

On Fri, Sep 06, 2019 at 05:57:17PM +0200, Arnd Bergmann wrote:
> It's never a good idea to put a 1000-byte buffer on the kernel
> stack. The compiler warns about this instance when usnic_ib_log_vf()
> gets inlined into usnic_ib_pci_probe():
>
> drivers/infiniband/hw/usnic/usnic_ib_main.c:543:12: error: stack frame size of 1044 bytes in function 'usnic_ib_pci_probe' [-Werror,-Wframe-larger-than=]
>
> As this is only called for debugging purposes in the setup path,
> it's trivial to convert to a dynamic allocation.
>
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> drivers/infiniband/hw/usnic/usnic_ib_main.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)

Applied to for-next, thanks

Jason