From: Coly Li <col...@suse.de>
[ 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 <col...@suse.de>
Signed-off-by: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Sasha Levin <sas...@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 28e0d5a5e25b..e5daf91310f6 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -290,7 +290,9 @@ 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
