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 289E1629 for ; Wed, 2 Nov 2022 03:30:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3373BC433D6; Wed, 2 Nov 2022 03:30:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1667359808; bh=jA5az3ARct8gCxZFxK53HFXyDiuM5Bb6LVmB5JuSNFQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FtmXE7LX1cPxMmU22YkRrs/qR+IZrHehs1JMy5hkXD+w6c17fFr6gTVmxz4Zi8169 TZJyrDamJJzc/zLqbjz4UbnNcYDH/NmQnFTJpFxlxpXY/UEAPw6sWCH4GOQlZm7XWR WrFNBr5UUlkTvnE8M1XvaPN6uKUwAgBKPAXYlaZU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Hyunwoo Kim , Helge Deller Subject: [PATCH 4.19 37/78] fbdev: smscufx: Fix several use-after-free bugs Date: Wed, 2 Nov 2022 03:34:22 +0100 Message-Id: <20221102022054.081323757@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221102022052.895556444@linuxfoundation.org> References: <20221102022052.895556444@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: Hyunwoo Kim commit cc67482c9e5f2c80d62f623bcc347c29f9f648e1 upstream. Several types of UAFs can occur when physically removing a USB device. Adds ufx_ops_destroy() function to .fb_destroy of fb_ops, and in this function, there is kref_put() that finally calls ufx_free(). This fix prevents multiple UAFs. Signed-off-by: Hyunwoo Kim Link: https://lore.kernel.org/linux-fbdev/20221011153436.GA4446@ubuntu/ Cc: Signed-off-by: Helge Deller Signed-off-by: Greg Kroah-Hartman --- drivers/video/fbdev/smscufx.c | 55 ++++++++++++++++++++++-------------------- 1 file changed, 30 insertions(+), 25 deletions(-) --- a/drivers/video/fbdev/smscufx.c +++ b/drivers/video/fbdev/smscufx.c @@ -100,7 +100,6 @@ struct ufx_data { struct kref kref; int fb_count; bool virtualized; /* true when physical usb device not present */ - struct delayed_work free_framebuffer_work; atomic_t usb_active; /* 0 = update virtual buffer, but no usb traffic */ atomic_t lost_pixels; /* 1 = a render op failed. Need screen refresh */ u8 *edid; /* null until we read edid from hw or get from sysfs */ @@ -1119,15 +1118,24 @@ static void ufx_free(struct kref *kref) { struct ufx_data *dev = container_of(kref, struct ufx_data, kref); - /* this function will wait for all in-flight urbs to complete */ - if (dev->urbs.count > 0) - ufx_free_urb_list(dev); + kfree(dev); +} - pr_debug("freeing ufx_data %p", dev); +static void ufx_ops_destory(struct fb_info *info) +{ + struct ufx_data *dev = info->par; + int node = info->node; - kfree(dev); + /* Assume info structure is freed after this point */ + framebuffer_release(info); + + pr_debug("fb_info for /dev/fb%d has been freed", node); + + /* release reference taken by kref_init in probe() */ + kref_put(&dev->kref, ufx_free); } + static void ufx_release_urb_work(struct work_struct *work) { struct urb_node *unode = container_of(work, struct urb_node, @@ -1136,14 +1144,9 @@ static void ufx_release_urb_work(struct up(&unode->dev->urbs.limit_sem); } -static void ufx_free_framebuffer_work(struct work_struct *work) +static void ufx_free_framebuffer(struct ufx_data *dev) { - struct ufx_data *dev = container_of(work, struct ufx_data, - free_framebuffer_work.work); struct fb_info *info = dev->info; - int node = info->node; - - unregister_framebuffer(info); if (info->cmap.len != 0) fb_dealloc_cmap(&info->cmap); @@ -1155,11 +1158,6 @@ static void ufx_free_framebuffer_work(st dev->info = NULL; - /* Assume info structure is freed after this point */ - framebuffer_release(info); - - pr_debug("fb_info for /dev/fb%d has been freed", node); - /* ref taken in probe() as part of registering framebfufer */ kref_put(&dev->kref, ufx_free); } @@ -1171,11 +1169,13 @@ static int ufx_ops_release(struct fb_inf { struct ufx_data *dev = info->par; + mutex_lock(&disconnect_mutex); + dev->fb_count--; /* We can't free fb_info here - fbmem will touch it when we return */ if (dev->virtualized && (dev->fb_count == 0)) - schedule_delayed_work(&dev->free_framebuffer_work, HZ); + ufx_free_framebuffer(dev); if ((dev->fb_count == 0) && (info->fbdefio)) { fb_deferred_io_cleanup(info); @@ -1189,6 +1189,8 @@ static int ufx_ops_release(struct fb_inf kref_put(&dev->kref, ufx_free); + mutex_unlock(&disconnect_mutex); + return 0; } @@ -1295,6 +1297,7 @@ static struct fb_ops ufx_ops = { .fb_blank = ufx_ops_blank, .fb_check_var = ufx_ops_check_var, .fb_set_par = ufx_ops_set_par, + .fb_destroy = ufx_ops_destory, }; /* Assumes &info->lock held by caller @@ -1678,9 +1681,6 @@ static int ufx_usb_probe(struct usb_inte goto destroy_modedb; } - INIT_DELAYED_WORK(&dev->free_framebuffer_work, - ufx_free_framebuffer_work); - retval = ufx_reg_read(dev, 0x3000, &id_rev); check_warn_goto_error(retval, "error %d reading 0x3000 register from device", retval); dev_dbg(dev->gdev, "ID_REV register value 0x%08x", id_rev); @@ -1753,10 +1753,12 @@ e_nomem: static void ufx_usb_disconnect(struct usb_interface *interface) { struct ufx_data *dev; + struct fb_info *info; mutex_lock(&disconnect_mutex); dev = usb_get_intfdata(interface); + info = dev->info; pr_debug("USB disconnect starting\n"); @@ -1770,12 +1772,15 @@ static void ufx_usb_disconnect(struct us /* if clients still have us open, will be freed on last close */ if (dev->fb_count == 0) - schedule_delayed_work(&dev->free_framebuffer_work, 0); + ufx_free_framebuffer(dev); - /* release reference taken by kref_init in probe() */ - kref_put(&dev->kref, ufx_free); + /* this function will wait for all in-flight urbs to complete */ + if (dev->urbs.count > 0) + ufx_free_urb_list(dev); - /* consider ufx_data freed */ + pr_debug("freeing ufx_data %p", dev); + + unregister_framebuffer(info); mutex_unlock(&disconnect_mutex); }