6.6-stable review patch. If anyone has any objections, please let me know.
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From: Oleksij Rempel o.rempel@pengutronix.de
[ Upstream commit 3ab8c5ed4f84fa20cd16794fe8dc31f633fbc70c ]
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: fadfd092ee91 ("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-v1-1-12fd0e... Signed-off-by: Alexandre Belloni alexandre.belloni@bootlin.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/rtc/rtc-pcf85063.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c index fdbc07f14036a..905986c616559 100644 --- a/drivers/rtc/rtc-pcf85063.c +++ b/drivers/rtc/rtc-pcf85063.c @@ -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,