From: Coly Li <colyli@xxxxxxx> [ Upstream commit 5b5fd3c94eef69dcfaa8648198e54c92e5687d6d ] 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@xxxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- 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 503ad954ccc0..d9481640b3e1 100644 --- a/drivers/md/bcache/sysfs.c +++ b/drivers/md/bcache/sysfs.c @@ -286,7 +286,9 @@ 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); -- 2.19.1
