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From: Coly Li <colyli@suse.de>
To: axboe@kernel.dk
Cc: linux-bcache@vger.kernel.org, linux-block@vger.kernel.org,
	Coly Li <colyli@suse.de>
Subject: [PATCH 07/19] bcache: improve sysfs_strtoul_clamp()
Date: Sat,  9 Feb 2019 12:52:59 +0800	[thread overview]
Message-ID: <20190209045311.15677-8-colyli@suse.de> (raw)
In-Reply-To: <20190209045311.15677-1-colyli@suse.de>

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>
---
 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 3fe82425859c..0ad2715a884e 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)						\
-- 
2.16.4


  parent reply	other threads:[~2019-02-09  4:53 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-09  4:52 [PATCH 00/19] bcache patches for Linux v5.1 Coly Li
2019-02-09  4:52 ` [PATCH 01/19] bcache: never writeback a discard operation Coly Li
2019-02-09  4:52 ` [PATCH 02/19] bcache: not use hard coded memset size in bch_cache_accounting_clear() Coly Li
2019-02-09  4:52 ` [PATCH 03/19] bcache: export backing_dev_name via sysfs Coly Li
2019-02-09  4:52 ` [PATCH 04/19] bcache: export backing_dev_uuid " Coly Li
2019-02-09  4:52 ` [PATCH 05/19] bcache: fix indentation issue, remove tabs on a hunk of code Coly Li
2019-02-09  4:52 ` [PATCH 06/19] bcache: treat stale && dirty keys as bad keys Coly Li
     [not found]   ` <20190212132825.E476F217D9@mail.kernel.org>
2019-02-12 16:42     ` Coly Li
2019-02-09  4:52 ` Coly Li [this message]
2019-02-09  4:53 ` [PATCH 08/19] bcache: fix input integer overflow of congested threshold Coly Li
2019-02-09  4:53 ` [PATCH 09/19] bcache: fix input overflow to sequential_cutoff Coly Li
2019-02-09  4:53 ` [PATCH 10/19] bcache: add sysfs_strtoul_bool() for setting bit-field variables Coly Li
2019-02-09  4:53 ` [PATCH 11/19] bcache: use sysfs_strtoul_bool() to set " Coly Li
2019-02-09  4:53 ` [PATCH 12/19] bcache: fix input overflow to writeback_delay Coly Li
2019-02-09  4:53 ` [PATCH 13/19] bcache: fix potential div-zero error of writeback_rate_i_term_inverse Coly Li
2019-02-09  4:53 ` [PATCH 14/19] bcache: fix potential div-zero error of writeback_rate_p_term_inverse Coly Li
2019-02-09  4:53 ` [PATCH 15/19] bcache: fix input overflow to writeback_rate_minimum Coly Li
2019-02-09  4:53 ` [PATCH 16/19] bcache: fix input overflow to journal_delay_ms Coly Li
2019-02-09  4:53 ` [PATCH 17/19] bcache: fix input overflow to cache set io_error_limit Coly Li
2019-02-09  4:53 ` [PATCH 18/19] bcache: fix input overflow to cache set sysfs file io_error_halflife Coly Li
2019-02-09  4:53 ` [PATCH 19/19] bcache: use (REQ_META|REQ_PRIO) to indicate bio for metadata Coly Li
     [not found]   ` <20190212132824.1D1502084E@mail.kernel.org>
2019-02-12 16:48     ` Coly Li
2019-02-09 14:19 ` [PATCH 00/19] bcache patches for Linux v5.1 Jens Axboe

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