[PATCH 5.10 150/300] 9p: fix /sys/fs/9p/caches overwriting itself

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

5.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Randall P. Embry <rpembry@gmail.com>

[ Upstream commit 86db0c32f16c5538ddb740f54669ace8f3a1f3d7 ]

caches_show() overwrote its buffer on each iteration,
so only the last cache tag was visible in sysfs output.

Properly append with snprintf(buf + count, …).

Signed-off-by: Randall P. Embry <rpembry@gmail.com>
Message-ID: <20250926-v9fs_misc-v1-2-a8b3907fc04d@codewreck.org>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/9p/v9fs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index 39def020a074b..b304e070139ca 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -558,7 +558,7 @@ static ssize_t caches_show(struct kobject *kobj,
 	spin_lock(&v9fs_sessionlist_lock);
 	list_for_each_entry(v9ses, &v9fs_sessionlist, slist) {
 		if (v9ses->cachetag) {
-			n = snprintf(buf, limit, "%s\n", v9ses->cachetag);
+			n = snprintf(buf + count, limit, "%s\n", v9ses->cachetag);
 			if (n < 0) {
 				count = n;
 				break;
-- 
2.51.0