From d9cd78edb2e6b7e26747c0ec312be31e7ef196fe Mon Sep 17 00:00:00 2001

From: Dan Carpenter <dan.carpenter@oracle.com>

Date: Thu, 22 Apr 2021 12:02:29 +0300

Subject: [PATCH] firmware: arm_scpi: Prevent the ternary sign expansion bug

Git-commit: d9cd78edb2e6b7e26747c0ec312be31e7ef196fe

Patch-mainline: v5.13-rc3

References: git-fixes

How the type promotion works in ternary expressions is a bit tricky.

The problem is that scpi_clk_get_val() returns longs, "ret" is a int

which holds a negative error code, and le32_to_cpu() is an unsigned int.

We want the negative error code to be cast to a negative long.  But

because le32_to_cpu() is an u32 then "ret" is type promoted to u32 and

becomes a high positive and then it is promoted to long and it is still

a high positive value.

Fix this by getting rid of the ternary.

Link: https://lore.kernel.org/r/YIE7pdqV/h10tEAK@mwanda

Fixes: 8cb7cf56c9fe ("firmware: add support for ARM System Control and Power Interface(SCPI) protocol")

Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

[sudeep.holla: changed to return 0 as clock rate on error]

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 drivers/firmware/arm_scpi.c | 4 +++-

 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/arm_scpi.c b/drivers/firmware/arm_scpi.c

index d0dee37ad522..4ceba5ef7895 100644

--- a/drivers/firmware/arm_scpi.c

+++ b/drivers/firmware/arm_scpi.c

@@ -552,8 +552,10 @@ static unsigned long scpi_clk_get_val(u16 clk_id)

 	ret = scpi_send_message(CMD_GET_CLOCK_VALUE, &le_clk_id,

 				sizeof(le_clk_id), &rate, sizeof(rate));

+	if (ret)

+		return 0;

-	return ret ? ret : le32_to_cpu(rate);

+	return le32_to_cpu(rate);

 }

 static int scpi_clk_set_val(u16 clk_id, unsigned long rate)

-- 

2.26.2