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From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Fuqian Huang <huangfq.daxian@gmail.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Sasha Levin <sashal@kernel.org>,
        linux-m68k@lists.linux-m68k.org
Subject: [PATCH AUTOSEL 5.4 016/330] m68k: q40: Fix info-leak in rtc_ioctl
Date:   Thu, 17 Sep 2020 21:55:56 -0400
Message-Id: <20200918020110.2063155-16-sashal@kernel.org>
In-Reply-To: <20200918020110.2063155-1-sashal@kernel.org>
References: <20200918020110.2063155-1-sashal@kernel.org>
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From: Fuqian Huang <huangfq.daxian@gmail.com>

[ Upstream commit 7cf78b6b12fd5550545e4b73b35dca18bd46b44c ]

When the option is RTC_PLL_GET, pll will be copied to userland
via copy_to_user. pll is initialized using mach_get_rtc_pll indirect
call and mach_get_rtc_pll is only assigned with function
q40_get_rtc_pll in arch/m68k/q40/config.c.
In function q40_get_rtc_pll, the field pll_ctrl is not initialized.
This will leak uninitialized stack content to userland.
Fix this by zeroing the uninitialized field.

Signed-off-by: Fuqian Huang <huangfq.daxian@gmail.com>
Link: https://lore.kernel.org/r/20190927121544.7650-1-huangfq.daxian@gmail.com
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/m68k/q40/config.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/m68k/q40/config.c b/arch/m68k/q40/config.c
index e63eb5f069995..f31890078197e 100644
--- a/arch/m68k/q40/config.c
+++ b/arch/m68k/q40/config.c
@@ -264,6 +264,7 @@ static int q40_get_rtc_pll(struct rtc_pll_info *pll)
 {
 	int tmp = Q40_RTC_CTRL;
 
+	pll->pll_ctrl = 0;
 	pll->pll_value = tmp & Q40_RTC_PLL_MASK;
 	if (tmp & Q40_RTC_PLL_SIGN)
 		pll->pll_value = -pll->pll_value;
-- 
2.25.1