From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D93D4848D for ; Fri, 10 Mar 2023 14:25:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 400B8C4339C; Fri, 10 Mar 2023 14:25:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678458307; bh=iLssFjCE/ZuSk8mC8YKfS8WArw1eZk+D/bVI0cb4e7k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wNfFJPy/qNSYGesAe4//I1SydVowfJeQMa7eCTM7s+YLMLtRIB4GbGrkTgWpAq5X/ bG8ZPL6RudQ9TK3l6B6Lxkt7F1Jtx4RgDKxhaXhBNuP3lw6h2DYf1V56aeQtpKEdo7 3F0ecuEKlyksOnf2fuOhKn74aSj98ykpjx1JMlfM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sven Schnelle , Jiri Slaby , Sasha Levin Subject: [PATCH 4.19 235/252] tty: fix out-of-bounds access in tty_driver_lookup_tty() Date: Fri, 10 Mar 2023 14:40:05 +0100 Message-Id: <20230310133726.483129785@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230310133718.803482157@linuxfoundation.org> References: <20230310133718.803482157@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Sven Schnelle [ Upstream commit db4df8e9d79e7d37732c1a1b560958e8dadfefa1 ] When specifying an invalid console= device like console=tty3270, tty_driver_lookup_tty() returns the tty struct without checking whether index is a valid number. To reproduce: qemu-system-x86_64 -enable-kvm -nographic -serial mon:stdio \ -kernel ../linux-build-x86/arch/x86/boot/bzImage \ -append "console=ttyS0 console=tty3270" This crashes with: [ 0.770599] BUG: kernel NULL pointer dereference, address: 00000000000000ef [ 0.771265] #PF: supervisor read access in kernel mode [ 0.771773] #PF: error_code(0x0000) - not-present page [ 0.772609] Oops: 0000 [#1] PREEMPT SMP PTI [ 0.774878] RIP: 0010:tty_open+0x268/0x6f0 [ 0.784013] chrdev_open+0xbd/0x230 [ 0.784444] ? cdev_device_add+0x80/0x80 [ 0.784920] do_dentry_open+0x1e0/0x410 [ 0.785389] path_openat+0xca9/0x1050 [ 0.785813] do_filp_open+0xaa/0x150 [ 0.786240] file_open_name+0x133/0x1b0 [ 0.786746] filp_open+0x27/0x50 [ 0.787244] console_on_rootfs+0x14/0x4d [ 0.787800] kernel_init_freeable+0x1e4/0x20d [ 0.788383] ? rest_init+0xc0/0xc0 [ 0.788881] kernel_init+0x11/0x120 [ 0.789356] ret_from_fork+0x22/0x30 Signed-off-by: Sven Schnelle Reviewed-by: Jiri Slaby Link: https://lore.kernel.org/r/20221209112737.3222509-2-svens@linux.ibm.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/tty_io.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index b6f42d0ee6269..d3e6b66155536 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1155,14 +1155,16 @@ static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver, { struct tty_struct *tty; - if (driver->ops->lookup) + if (driver->ops->lookup) { if (!file) tty = ERR_PTR(-EIO); else tty = driver->ops->lookup(driver, file, idx); - else + } else { + if (idx >= driver->num) + return ERR_PTR(-EINVAL); tty = driver->ttys[idx]; - + } if (!IS_ERR(tty)) tty_kref_get(tty); return tty; -- 2.39.2