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From:   Philipp Stanner <pstanner@redhat.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Philipp Stanner <pstanner@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Kefeng Wang <wangkefeng.wang@huawei.com>,
        Tony Luck <tony.luck@intel.com>,
        Ard Biesheuvel <ardb@kernel.org>
Cc:     linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
        Dave Airlie <airlied@redhat.com>
Subject: [PATCH] drivers/tty/vt: copy userspace arrays safely
Date:   Thu,  2 Nov 2023 20:21:35 +0100
Message-ID: <20231102192134.53301-2-pstanner@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The functions (v)memdup_user() are utilized to copy userspace arrays.
This is done without overflow checks.

Use the new wrappers memdup_array_user() and vmemdup_array_user() to
copy the arrays more safely.

Suggested-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
---
 drivers/tty/vt/consolemap.c | 2 +-
 drivers/tty/vt/keyboard.c   | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c
index f02d21e2a96e..313cef3322eb 100644
--- a/drivers/tty/vt/consolemap.c
+++ b/drivers/tty/vt/consolemap.c
@@ -644,7 +644,7 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)
 	if (!ct)
 		return 0;
 
-	unilist = vmemdup_user(list, array_size(sizeof(*unilist), ct));
+	unilist = vmemdup_array_user(list, ct, sizeof(*unilist));
 	if (IS_ERR(unilist))
 		return PTR_ERR(unilist);
 
diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index 1fe6107b539b..802ceb0a5e4c 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -1773,8 +1773,8 @@ int vt_do_diacrit(unsigned int cmd, void __user *udp, int perm)
 
 		if (ct) {
 
-			dia = memdup_user(a->kbdiacr,
-					sizeof(struct kbdiacr) * ct);
+			dia = memdup_array_user(a->kbdiacr,
+						ct, sizeof(struct kbdiacr));
 			if (IS_ERR(dia))
 				return PTR_ERR(dia);
 
@@ -1811,8 +1811,8 @@ int vt_do_diacrit(unsigned int cmd, void __user *udp, int perm)
 			return -EINVAL;
 
 		if (ct) {
-			buf = memdup_user(a->kbdiacruc,
-					  ct * sizeof(struct kbdiacruc));
+			buf = memdup_array_user(a->kbdiacruc,
+						ct, sizeof(struct kbdiacruc));
 			if (IS_ERR(buf))
 				return PTR_ERR(buf);
 		} 
-- 
2.41.0