From: Coly Li Date: Sat, 9 Feb 2019 04:52:59 +0000 (+0800) Subject: bcache: improve sysfs_strtoul_clamp() X-Git-Tag: v5.15~6749^2~89 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=596b5a5dd1bc2fa019fdaaae522ef331deef927f;p=platform%2Fkernel%2Flinux-starfive.git bcache: improve sysfs_strtoul_clamp() 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 Signed-off-by: Jens Axboe --- diff --git a/drivers/md/bcache/sysfs.h b/drivers/md/bcache/sysfs.h index 3fe8242..0ad2715 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) \