Commit a91fbda4 authored Feb 09, 2019 by Coly Li Committed by Jens Axboe Feb 09, 2019

bcache: fix input overflow to cache set sysfs file io_error_halflife



Cache set sysfs entry io_error_halflife is used to set c->error_decay.
c->error_decay is in type unsigned int, and it is converted by
strtoul_or_return(), therefore overflow to c->error_decay is possible
for a large input value.

This patch fixes the overflow by using strtoul_safe_clamp() to convert
input string to an unsigned long value in range [0, UINT_MAX], then
divides by 88 and set it to c->error_decay.

Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent b1500840

drivers/md/bcache/sysfs.c

+11 −2

Original line number	Diff line number	Diff line
		@@ -804,8 +804,17 @@ STORE(__bch_cache_set)
		sysfs_strtoul_clamp(io_error_limit, c->error_limit, 0, UINT_MAX);

		/* See count_io_errors() for why 88 */
		if (attr == &sysfs_io_error_halflife)
		c->error_decay = strtoul_or_return(buf) / 88;
		if (attr == &sysfs_io_error_halflife) {
		unsigned long v = 0;
		ssize_t ret;

		ret = strtoul_safe_clamp(buf, v, 0, UINT_MAX);
		if (!ret) {
		c->error_decay = v / 88;
		return size;
		}
		return ret;
		}

		if (attr == &sysfs_io_disable) {
		v = strtoul_or_return(buf);

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