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rtc: pcf85063: fix potential OOB write in PCF85063 NVMEM read

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[ Upstream commit 3ab8c5ed4f ]

The nvmem interface supports variable buffer sizes, while the regmap
interface operates with fixed-size storage. If an nvmem client uses a
buffer size less than 4 bytes, regmap_read will write out of bounds
as it expects the buffer to point at an unsigned int.

Fix this by using an intermediary unsigned int to hold the value.

Fixes: fadfd092ee ("rtc: pcf85063: add nvram support")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.kernel.org/r/20241218-rtc-pcf85063-stack-corruption-v1-1-12fd0ee0f046@pengutronix.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Oleksij Rempel
2024-12-18 20:34:58 +01:00
committed by Greg Kroah-Hartman
parent c6e1b2cac2
commit 9adefa7b95
1 changed files with 10 additions and 1 deletions
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drivers/rtc/rtc-pcf85063.c
+10 -1
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@@ -322,7 +322,16 @@ static const struct rtc_class_ops pcf85063_rtc_ops = {
static int pcf85063_nvmem_read(void *priv, unsigned int offset,
void *val, size_t bytes)
{
return regmap_read(priv, PCF85063_REG_RAM, val);
unsigned int tmp;
int ret;
ret = regmap_read(priv, PCF85063_REG_RAM, &tmp);
if (ret < 0)
return ret;
*(u8 *)val = tmp;
return 0;
}
static int pcf85063_nvmem_write(void *priv, unsigned int offset,