'type' is a user-controlled value used to index into 's_qf_names', which
can be used in a Spectre v1 attack. Clamp 'type' to the size of the
array to avoid a speculative out-of-bounds read.
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jeremy Cline <jcline@xxxxxxxxxx>
---
fs/ext4/super.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 6480e763080f..c04a09b51742 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -40,6 +40,7 @@
#include <linux/crc16.h>
#include <linux/dax.h>
#include <linux/cleancache.h>
+#include <linux/nospec.h>
#include <linux/uaccess.h>
#include <linux/iversion.h>
@@ -5559,6 +5560,7 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id,
if (path->dentry->d_sb != sb)
return -EXDEV;
/* Journaling quota? */
+ type = array_index_nospec(type, EXT4_MAXQUOTAS);
if (EXT4_SB(sb)->s_qf_names[type]) {
/* Quotafile not in fs root? */
if (path->dentry->d_parent != sb->s_root)
--
2.17.1
