linux-kernel - [PATCH 1/2] regmap: Fix reversed bounds check in regmap_raw

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Date:   Thu, 8 Feb 2018 10:23:44 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Mark Brown <broonie@...nel.org>,
        Markus Pargmann <mpa@...gutronix.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH 1/2] regmap: Fix reversed bounds check in regmap_raw_write()

We're supposed to be checking that "val_len" is not too large but
instead we check if it is smaller than the max.

The only function affected would be regmap_i2c_smbus_i2c_write() in
drivers/base/regmap/regmap-i2c.c.  Strangely that function has its own
limit check which returns an error if (count >= I2C_SMBUS_BLOCK_MAX) so
it doesn't look like it has ever been able to do anything except return
an error.

Fixes: c335931ed9d2 ("regmap: Add raw_write/read checks for max_raw_write/read sizes")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
This is from code review.  I can't test it.

Is it possible that there are other ways to reach
regmap_i2c_smbus_i2c_write() without going through regmap_raw_write()?
In that case, the temptation would be to just remove this check and the
one in regmap_raw_read().

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index ee302ccdfbc8..453116fd4362 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1831,7 +1831,7 @@ int regmap_raw_write(struct regmap *map, unsigned int reg,
 		return -EINVAL;
 	if (val_len % map->format.val_bytes)
 		return -EINVAL;
-	if (map->max_raw_write && map->max_raw_write > val_len)
+	if (map->max_raw_write && map->max_raw_write < val_len)
 		return -E2BIG;

 	map->lock(map->lock_arg);