linux-kernel - [PATCH] usnic: avoid overly large buffers on stack

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Message-Id: <20190906155730.2750200-1-arnd@arndb.de>
Date:   Fri,  6 Sep 2019 17:57:17 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Christian Benvenuti <benve@...co.com>,
        Nelson Escobar <neescoba@...co.com>,
        Parvi Kaustubhi <pkaustub@...co.com>,
        Doug Ledford <dledford@...hat.com>,
        Jason Gunthorpe <jgg@...pe.ca>
Cc:     Arnd Bergmann <arnd@...db.de>, Leon Romanovsky <leon@...nel.org>,
        Gal Pressman <galpress@...zon.com>,
        Parav Pandit <parav@...lanox.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Kamal Heib <kamalheib1@...il.com>,
        Florian Westphal <fw@...len.de>, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org
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 <arnd@...db.de>
---
 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