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authorColy Li <colyli@suse.de>2019-02-09 12:53:06 +0800
committerJens Axboe <axboe@kernel.dk>2019-02-09 07:18:32 -0700
commit5b5fd3c94eef69dcfaa8648198e54c92e5687d6d (patch)
tree07a4cb19bc9bac91653046d86d64c0fc6a06ee4a /drivers/md
parentc3b75a2199cdbfc1c335155fe143d842604b1baa (diff)
bcache: fix potential div-zero error of writeback_rate_p_term_inverse
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> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/bcache/sysfs.c4
1 files changed, 3 insertions, 1 deletions
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);