From: Jeremy Cline Subject: [PATCH 1/3] ext4: super: Fix spectre gadget in ext4_quota_on Date: Fri, 27 Jul 2018 16:23:55 +0000 Message-ID: <20180727162357.30801-2-jcline@redhat.com> References: <20180727162357.30801-1-jcline@redhat.com> Cc: Josh Poimboeuf , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, Jeremy Cline , stable@vger.kernel.org To: Theodore Ts'o , Andreas Dilger Return-path: In-Reply-To: <20180727162357.30801-1-jcline@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org '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 Cc: stable@vger.kernel.org Signed-off-by: Jeremy Cline --- 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 #include #include +#include #include #include @@ -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