[PATCH AUTOSEL 4.19 05/32] i2c: bail out early when RDWR parameters are wrong

[PATCH AUTOSEL 4.19 05/32] i2c: bail out early when RDWR parameters are wrong

[Sasha Levin]

From: Wolfram Sang <wsa+renesas@sang-engineering.com>

[ Upstream commit 71581562ee36032d2d574a9b23ad4af6d6a64cf7 ]

The buggy parameters currently get caught later, but emit a noisy WARN.
Userspace should not be able to trigger this, so add similar checks much
earlier. Also avoids some unneeded code paths, of course. Apply kernel
coding stlye to a comment while here.

Reported-by: syzbot+ffb0b3ffa6cfbc7d7b3f@syzkaller.appspotmail.com
Tested-by: syzbot+ffb0b3ffa6cfbc7d7b3f@syzkaller.appspotmail.com
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/i2c/i2c-dev.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index cbda91a0cb5f..1d10ee86299d 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -448,8 +448,13 @@ static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 				   sizeof(rdwr_arg)))
 			return -EFAULT;
 
-		/* Put an arbitrary limit on the number of messages that can
-		 * be sent at once */
+		if (!rdwr_arg.msgs || rdwr_arg.nmsgs == 0)
+			return -EINVAL;
+
+		/*
+		 * Put an arbitrary limit on the number of messages that can
+		 * be sent at once
+		 */
 		if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
 			return -EINVAL;
 
-- 
2.30.2

[PATCH AUTOSEL 4.19 16/32] i2c: Add I2C_AQ_NO_REP_START adapter quirk

[Sasha Levin]

From: Bence Csókás <bence98@sch.bme.hu>

[ Upstream commit aca01415e076aa96cca0f801f4420ee5c10c660d ]

This quirk signifies that the adapter cannot do a repeated
START, it always issues a STOP condition after transfers.

Suggested-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Bence Csókás <bence98@sch.bme.hu>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/i2c.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 7e748648c7d3..6fda0458745d 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -662,6 +662,8 @@ struct i2c_adapter_quirks {
 #define I2C_AQ_NO_ZERO_LEN_READ		BIT(5)
 #define I2C_AQ_NO_ZERO_LEN_WRITE	BIT(6)
 #define I2C_AQ_NO_ZERO_LEN		(I2C_AQ_NO_ZERO_LEN_READ | I2C_AQ_NO_ZERO_LEN_WRITE)
+/* adapter cannot do repeated START */
+#define I2C_AQ_NO_REP_START		BIT(7)
 
 /*
  * i2c_adapter is the structure used to identify a physical i2c bus along
-- 
2.30.2