It is reported that sysfs buffer overflow can be triggered in case of too many CPU cores(>841 on 4K PAGE_SIZE) when showing CPUs in blk_mq_hw_sysfs_cpus_show().
So use cpumap_print_to_pagebuf() to print the info and fix the potential buffer overflow issue. Cc: [email protected] Cc: Mark Ray <[email protected]> Cc: Greg KH <[email protected]> Fixes: 676141e48af7("blk-mq: don't dump CPU -> hw queue map on driver load") Signed-off-by: Ming Lei <[email protected]> --- block/blk-mq-sysfs.c | 15 +-------------- 1 file changed, 1 insertion(+), 14 deletions(-) diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c index d6e1a9bd7131..4d0d32377ba3 100644 --- a/block/blk-mq-sysfs.c +++ b/block/blk-mq-sysfs.c @@ -166,20 +166,7 @@ static ssize_t blk_mq_hw_sysfs_nr_reserved_tags_show(struct blk_mq_hw_ctx *hctx, static ssize_t blk_mq_hw_sysfs_cpus_show(struct blk_mq_hw_ctx *hctx, char *page) { - unsigned int i, first = 1; - ssize_t ret = 0; - - for_each_cpu(i, hctx->cpumask) { - if (first) - ret += sprintf(ret + page, "%u", i); - else - ret += sprintf(ret + page, ", %u", i); - - first = 0; - } - - ret += sprintf(ret + page, "\n"); - return ret; + return cpumap_print_to_pagebuf(true, page, hctx->cpumask); } static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_nr_tags = { -- 2.20.1
