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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 14/19] bcache: fix potential div-zero error of writeback_rate_p_term_inverse
Date: Sat,  9 Feb 2019 12:53:06 +0800	[thread overview]
Message-ID: <20190209045311.15677-15-colyli@suse.de> (raw)
In-Reply-To: <20190209045311.15677-1-colyli@suse.de>

Current code already uses d_strtoul_nonzero() to convert input string
to an unsigned integer, to make sure writeback_rate_p_term_inverse
won't be zero value. But overflow may happen when converting input
string to an unsigned integer value by d_strtoul_nonzero(), then
dc->writeback_rate_p_term_inverse can still be set to 0 even if the
sysfs file input value is not zero, e.g. 4294967296 (a.k.a UINT_MAX+1).

If dc->writeback_rate_p_term_inverse is set to 0, it might cause a
dev-zero error in following code from __update_writeback_rate(),
	int64_t proportional_scaled =
		div_s64(error, dc->writeback_rate_p_term_inverse);

This patch replaces d_strtoul_nonzero() by sysfs_strtoul_clamp() and
limit the value range in [1, UINT_MAX]. Then the unsigned integer
overflow and dev-zero error can be avoided.

Signed-off-by: Coly Li <colyli@suse.de>
---
 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 0fad46d3a8bd..c6677c93e368 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -305,7 +305,9 @@ STORE(__cached_dev)
 	sysfs_strtoul_clamp(writeback_rate_i_term_inverse,
 			    dc->writeback_rate_i_term_inverse,
 			    1, UINT_MAX);
-	d_strtoul_nonzero(writeback_rate_p_term_inverse);
+	sysfs_strtoul_clamp(writeback_rate_p_term_inverse,
+			    dc->writeback_rate_p_term_inverse,
+			    1, UINT_MAX);
 	d_strtoul_nonzero(writeback_rate_minimum);
 
 	sysfs_strtoul_clamp(io_error_limit, dc->error_limit, 0, INT_MAX);
-- 
2.16.4


  parent reply	other threads:[~2019-02-09  4:54 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 ` [PATCH 07/19] bcache: improve sysfs_strtoul_clamp() Coly Li
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 ` Coly Li [this message]
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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