linux-kernel - [PATCH 4.4 87/88] rocker: fix rocker_tlv_put

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Date:   Fri, 14 Dec 2018 13:01:01 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.4 87/88] rocker: fix rocker_tlv_put_* functions for KASAN

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arnd Bergmann <arnd@...db.de>

commit 6098d7ddd62f532f80ee2a4b01aca500a8e4e9e4 upstream.

Inlining these functions creates lots of stack variables that each take
64 bytes when KASAN is enabled, leading to this warning about potential
stack overflow:

drivers/net/ethernet/rocker/rocker_ofdpa.c: In function 'ofdpa_cmd_flow_tbl_add':
drivers/net/ethernet/rocker/rocker_ofdpa.c:621:1: error: the frame size of 2752 bytes is larger than 1536 bytes [-Werror=frame-larger-than=]

gcc-8 can now consolidate the stack slots itself, but on older versions
we get the same behavior by using a temporary variable that holds a
copy of the inline function argument.

Cc: stable@...r.kernel.org
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/ethernet/rocker/rocker.c |   24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

--- a/drivers/net/ethernet/rocker/rocker.c
+++ b/drivers/net/ethernet/rocker/rocker.c
@@ -821,37 +821,49 @@ static int rocker_tlv_put(struct rocker_
 static int rocker_tlv_put_u8(struct rocker_desc_info *desc_info,
 			     int attrtype, u8 value)
 {
-	return rocker_tlv_put(desc_info, attrtype, sizeof(u8), &value);
+	u8 tmp = value; /* work around GCC PR81715 */
+
+	return rocker_tlv_put(desc_info, attrtype, sizeof(u8), &tmp);
 }
 
 static int rocker_tlv_put_u16(struct rocker_desc_info *desc_info,
 			      int attrtype, u16 value)
 {
-	return rocker_tlv_put(desc_info, attrtype, sizeof(u16), &value);
+	u16 tmp = value;
+
+	return rocker_tlv_put(desc_info, attrtype, sizeof(u16), &tmp);
 }
 
 static int rocker_tlv_put_be16(struct rocker_desc_info *desc_info,
 			       int attrtype, __be16 value)
 {
-	return rocker_tlv_put(desc_info, attrtype, sizeof(__be16), &value);
+	__be16 tmp = value;
+
+	return rocker_tlv_put(desc_info, attrtype, sizeof(__be16), &tmp);
 }
 
 static int rocker_tlv_put_u32(struct rocker_desc_info *desc_info,
 			      int attrtype, u32 value)
 {
-	return rocker_tlv_put(desc_info, attrtype, sizeof(u32), &value);
+	u32 tmp = value;
+
+	return rocker_tlv_put(desc_info, attrtype, sizeof(u32), &tmp);
 }
 
 static int rocker_tlv_put_be32(struct rocker_desc_info *desc_info,
 			       int attrtype, __be32 value)
 {
-	return rocker_tlv_put(desc_info, attrtype, sizeof(__be32), &value);
+	__be32 tmp = value;
+
+	return rocker_tlv_put(desc_info, attrtype, sizeof(__be32), &tmp);
 }
 
 static int rocker_tlv_put_u64(struct rocker_desc_info *desc_info,
 			      int attrtype, u64 value)
 {
-	return rocker_tlv_put(desc_info, attrtype, sizeof(u64), &value);
+	u64 tmp = value;
+
+	return rocker_tlv_put(desc_info, attrtype, sizeof(u64), &tmp);
 }
 
 static struct rocker_tlv *