[PATCH AUTOSEL 4.14 075/123] bcache: fix input overflow to cache set sysfs file io_error_halflife

[PATCH AUTOSEL 4.14 075/123] bcache: fix input overflow to cache set sysfs file io_error_halflife

[Sasha Levin]

From: Coly Li <colyli@suse.de>

[ Upstream commit a91fbda49f746119828f7e8ad0f0aa2ab0578f65 ]

Cache set sysfs entry io_error_halflife is used to set c->error_decay.
c->error_decay is in type unsigned int, and it is converted by
strtoul_or_return(), therefore overflow to c->error_decay is possible
for a large input value.

This patch fixes the overflow by using strtoul_safe_clamp() to convert
input string to an unsigned long value in range [0, UINT_MAX], then
divides by 88 and set it to c->error_decay.

Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/md/bcache/sysfs.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 5d81cd06af00..43ff7fbcbc7c 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -660,8 +660,17 @@ STORE(__bch_cache_set)
 		c->error_limit = strtoul_or_return(buf) << IO_ERROR_SHIFT;
 
 	/* See count_io_errors() for why 88 */
-	if (attr == &sysfs_io_error_halflife)
-		c->error_decay = strtoul_or_return(buf) / 88;
+	if (attr == &sysfs_io_error_halflife) {
+		unsigned long v = 0;
+		ssize_t ret;
+
+		ret = strtoul_safe_clamp(buf, v, 0, UINT_MAX);
+		if (!ret) {
+			c->error_decay = v / 88;
+			return size;
+		}
+		return ret;
+	}
 
 	sysfs_strtoul(journal_delay_ms,		c->journal_delay_ms);
 	sysfs_strtoul(verify,			c->verify);
-- 
2.19.1

[PATCH AUTOSEL 4.14 076/123] bcache: fix input overflow to sequential_cutoff

[Sasha Levin]

From: Coly Li <colyli@suse.de>

[ Upstream commit 8c27a3953e92eb0b22dbb03d599f543a05f9574e ]

People may set sequential_cutoff of a cached device via sysfs file,
but current code does not check input value overflow. E.g. if value
4294967295 (UINT_MAX) is written to file sequential_cutoff, its value
is 4GB, but if 4294967296 (UINT_MAX + 1) is written into, its value
will be 0. This is an unexpected behavior.

This patch replaces d_strtoi_h() by sysfs_strtoul_clamp() to convert
input string to unsigned integer value, and limit its range in
[0, UINT_MAX]. Then the input overflow can be fixed.

Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/md/bcache/sysfs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 43ff7fbcbc7c..def9c3478b89 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -217,7 +217,9 @@ STORE(__cached_dev)
 	d_strtoul(writeback_rate_d_term);
 	d_strtoul_nonzero(writeback_rate_p_term_inverse);
 
-	d_strtoi_h(sequential_cutoff);
+	sysfs_strtoul_clamp(sequential_cutoff,
+			    dc->sequential_cutoff,
+			    0, UINT_MAX);
 	d_strtoi_h(readahead);
 
 	if (attr == &sysfs_clear_stats)
-- 
2.19.1

[PATCH AUTOSEL 4.14 077/123] bcache: improve sysfs_strtoul_clamp()

[Sasha Levin]

From: Coly Li <colyli@suse.de>

[ Upstream commit 596b5a5dd1bc2fa019fdaaae522ef331deef927f ]

Currently sysfs_strtoul_clamp() is defined as,
 82 #define sysfs_strtoul_clamp(file, var, min, max)                   \
 83 do {                                                               \
 84         if (attr == &sysfs_ ## file)                               \
 85                 return strtoul_safe_clamp(buf, var, min, max)      \
 86                         ?: (ssize_t) size;                         \
 87 } while (0)

The problem is, if bit width of var is less then unsigned long, min and
max may not protect var from integer overflow, because overflow happens
in strtoul_safe_clamp() before checking min and max.

To fix such overflow in sysfs_strtoul_clamp(), to make min and max take
effect, this patch adds an unsigned long variable, and uses it to macro
strtoul_safe_clamp() to convert an unsigned long value in range defined
by [min, max]. Then assign this value to var. By this method, if bit
width of var is less than unsigned long, integer overflow won't happen
before min and max are checking.

Now sysfs_strtoul_clamp() can properly handle smaller data type like
unsigned int, of cause min and max should be defined in range of
unsigned int too.

Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/md/bcache/sysfs.h | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/md/bcache/sysfs.h b/drivers/md/bcache/sysfs.h
index b54fe9602529..e6e258f897ca 100644
--- a/drivers/md/bcache/sysfs.h
+++ b/drivers/md/bcache/sysfs.h
@@ -81,9 +81,16 @@ do {									\
 
 #define sysfs_strtoul_clamp(file, var, min, max)			\
 do {									\
-	if (attr == &sysfs_ ## file)					\
-		return strtoul_safe_clamp(buf, var, min, max)		\
-			?: (ssize_t) size;				\
+	if (attr == &sysfs_ ## file) {					\
+		unsigned long v = 0;					\
+		ssize_t ret;						\
+		ret = strtoul_safe_clamp(buf, v, min, max);		\
+		if (!ret) {						\
+			var = v;					\
+			return size;					\
+		}							\
+		return ret;						\
+	}								\
 } while (0)
 
 #define strtoul_or_return(cp)						\
-- 
2.19.1