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From: Ming Lei <ming.lei@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, Ming Lei <ming.lei@redhat.com>,
	stable@vger.kernel.org, Mark Ray <mark.ray@hpe.com>,
	Greg KH <gregkh@linuxfoundation.org>
Subject: [PATCH] blk-mq: remove blk_mq_hw_sysfs_cpus
Date: Fri, 16 Aug 2019 15:48:49 +0800
Message-ID: <20190816074849.7197-1-ming.lei@redhat.com> (raw)

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().

This info isn't useful, given users may retrieve the CPU list
from sw queue entries under same kobject dir, so far not see
any active users.

So remove the entry as suggested by Greg.

Cc: stable@vger.kernel.org
Cc: Mark Ray <mark.ray@hpe.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Fixes: 676141e48af7("blk-mq: don't dump CPU -> hw queue map on driver load")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 block/blk-mq-sysfs.c | 23 -----------------------
 1 file changed, 23 deletions(-)

diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index d6e1a9bd7131..e0b97c22726c 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -164,24 +164,6 @@ static ssize_t blk_mq_hw_sysfs_nr_reserved_tags_show(struct blk_mq_hw_ctx *hctx,
 	return sprintf(page, "%u\n", hctx->tags->nr_reserved_tags);
 }
 
-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;
-}
-
 static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_nr_tags = {
 	.attr = {.name = "nr_tags", .mode = 0444 },
 	.show = blk_mq_hw_sysfs_nr_tags_show,
@@ -190,15 +172,10 @@ static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_nr_reserved_tags = {
 	.attr = {.name = "nr_reserved_tags", .mode = 0444 },
 	.show = blk_mq_hw_sysfs_nr_reserved_tags_show,
 };
-static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_cpus = {
-	.attr = {.name = "cpu_list", .mode = 0444 },
-	.show = blk_mq_hw_sysfs_cpus_show,
-};
 
 static struct attribute *default_hw_ctx_attrs[] = {
 	&blk_mq_hw_sysfs_nr_tags.attr,
 	&blk_mq_hw_sysfs_nr_reserved_tags.attr,
-	&blk_mq_hw_sysfs_cpus.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(default_hw_ctx);
-- 
2.20.1


             reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-16  7:48 Ming Lei [this message]
2019-08-16  8:12 ` Greg KH
2019-08-16 14:20 ` Jens Axboe
2019-08-16 14:54   ` Greg KH
2019-08-16 15:12     ` Jens Axboe
2019-08-16 15:21       ` Greg KH
2019-08-16 16:08   ` Ming Lei

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