[PATCH AUTOSEL 5.10 1/2] orangefs: fix a oob in orangefs_debug_write

[Sasha Levin]

From: Mike Marshall <hubcap@xxxxxxxxxxxx>

[ Upstream commit f7c848431632598ff9bce57a659db6af60d75b39 ]

I got a syzbot report: slab-out-of-bounds Read in
orangefs_debug_write... several people suggested fixes,
I tested Al Viro's suggestion and made this patch.

Signed-off-by: Mike Marshall <hubcap@xxxxxxxxxxxx>
Reported-by: syzbot+fc519d7875f2d9186c1f@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/orangefs/orangefs-debugfs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/orangefs/orangefs-debugfs.c b/fs/orangefs/orangefs-debugfs.c
index 1b508f5433846..fa41db0884880 100644
--- a/fs/orangefs/orangefs-debugfs.c
+++ b/fs/orangefs/orangefs-debugfs.c
@@ -393,9 +393,9 @@ static ssize_t orangefs_debug_write(struct file *file,
 	 * Thwart users who try to jamb a ridiculous number
 	 * of bytes into the debug file...
 	 */
-	if (count > ORANGEFS_MAX_DEBUG_STRING_LEN + 1) {
+	if (count > ORANGEFS_MAX_DEBUG_STRING_LEN) {
 		silly = count;
-		count = ORANGEFS_MAX_DEBUG_STRING_LEN + 1;
+		count = ORANGEFS_MAX_DEBUG_STRING_LEN;
 	}
 
 	buf = kzalloc(ORANGEFS_MAX_DEBUG_STRING_LEN, GFP_KERNEL);
-- 
2.39.5