linux-kernel - [PATCH] m68k: q40: Fix info-leak in rtc

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Message-Id: <20190927121544.7650-1-huangfq.daxian@gmail.com>
Date:   Fri, 27 Sep 2019 20:15:44 +0800
From:   Fuqian Huang <huangfq.daxian@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org,
        Fuqian Huang <huangfq.daxian@...il.com>
Subject: [PATCH] m68k: q40: Fix info-leak in rtc_ioctl

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@...il.com>
---
 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 e63eb5f06999..f31890078197 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;
-- 
2.11.0