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Date: Tue, 10 Apr 2018 18:03:30 -0700
From: Laura Abbott <labbott@...hat.com>
To: Russell King <linux@...linux.org.uk>,
David Airlie <airlied@...ux.ie>
Cc: Laura Abbott <labbott@...hat.com>,
dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com,
Kees Cook <keescook@...omium.org>
Subject: [PATCHv2] drm/i2c: tda998x: Remove VLA usage
There's an ongoing effort to remove VLAs[1] from the kernel to eventually
turn on -Wvla. The vla in reg_write_range is based on the length of data
passed. The one use of a non-constant size for this range is bounded by
the size buffer passed to hdmi_infoframe_pack which is a fixed size.
Switch to this upper bound.
[1] https://lkml.org/lkml/2018/3/7/621
Signed-off-by: Laura Abbott <labbott@...hat.com>
---
v2: Switch to make the buffer size more transparent and add a bounds
check.
---
drivers/gpu/drm/i2c/tda998x_drv.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
index 9e67a7b4e3a4..c8b6029b7839 100644
--- a/drivers/gpu/drm/i2c/tda998x_drv.c
+++ b/drivers/gpu/drm/i2c/tda998x_drv.c
@@ -466,13 +466,22 @@ reg_read_range(struct tda998x_priv *priv, u16 reg, char *buf, int cnt)
return ret;
}
+#define MAX_WRITE_RANGE_BUF 32
+
static void
reg_write_range(struct tda998x_priv *priv, u16 reg, u8 *p, int cnt)
{
struct i2c_client *client = priv->hdmi;
- u8 buf[cnt+1];
+ /* This is the maximum size of the buffer passed in */
+ u8 buf[MAX_WRITE_RANGE_BUF + 1];
int ret;
+ if (cnt > MAX_WRITE_RANGE_BUF) {
+ dev_err(&client->dev, "Fixed write buffer too small (%d)\n",
+ MAX_WRITE_RANGE_BUF);
+ return;
+ }
+
buf[0] = REG2ADDR(reg);
memcpy(&buf[1], p, cnt);
@@ -679,7 +688,7 @@ static void
tda998x_write_if(struct tda998x_priv *priv, u8 bit, u16 addr,
union hdmi_infoframe *frame)
{
- u8 buf[32];
+ u8 buf[MAX_WRITE_RANGE_BUF];
ssize_t len;
len = hdmi_infoframe_pack(frame, buf, sizeof(buf));
--
2.14.3
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