linux-hardening - [PATCH] block: Replace all non-returning strlcpy with strscpy

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Date:   Tue, 30 May 2023 15:56:08 +0000
From:   Azeem Shaikh <azeemshaikh38@...il.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-hardening@...r.kernel.org,
        Azeem Shaikh <azeemshaikh38@...il.com>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] block: Replace all non-returning strlcpy with strscpy

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
No return values were used, so direct replacement is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@...il.com>
---
 block/blk-cgroup-fc-appid.c |    2 +-
 block/elevator.c            |    2 +-
 block/genhd.c               |    2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/block/blk-cgroup-fc-appid.c b/block/blk-cgroup-fc-appid.c
index 842e5e1c0f3c..3ec21333f393 100644
--- a/block/blk-cgroup-fc-appid.c
+++ b/block/blk-cgroup-fc-appid.c
@@ -34,7 +34,7 @@ int blkcg_set_fc_appid(char *app_id, u64 cgrp_id, size_t app_id_len)
 	 * the vmid from the fabric.
 	 * Adding the overhead of a lock is not necessary.
 	 */
-	strlcpy(blkcg->fc_app_id, app_id, app_id_len);
+	strscpy(blkcg->fc_app_id, app_id, app_id_len);
 	css_put(css);
 out_cgrp_put:
 	cgroup_put(cgrp);
diff --git a/block/elevator.c b/block/elevator.c
index 24909069f872..8400e303fbcb 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -751,7 +751,7 @@ ssize_t elv_iosched_store(struct request_queue *q, const char *buf,
 	if (!elv_support_iosched(q))
 		return count;
 
-	strlcpy(elevator_name, buf, sizeof(elevator_name));
+	strscpy(elevator_name, buf, sizeof(elevator_name));
 	ret = elevator_change(q, strstrip(elevator_name));
 	if (!ret)
 		return count;
diff --git a/block/genhd.c b/block/genhd.c
index 1cb489b927d5..3537b7d7c484 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -253,7 +253,7 @@ int __register_blkdev(unsigned int major, const char *name,
 #ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
 	p->probe = probe;
 #endif
-	strlcpy(p->name, name, sizeof(p->name));
+	strscpy(p->name, name, sizeof(p->name));
 	p->next = NULL;
 	index = major_to_index(major);