linux-kernel - [PATCH] fb: sh-mobile: Fix deadlock risk between lock_fb_info() and console

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 2 Sep 2011 19:24:03 +0200
From:	Bruno Prémont <bonbons@...ux-vserver.org>
To:	Florian Tobias Schandinat <FlorianSchandinat@....de>
Cc:	Guennadi Liakhovetski <g.liakhovetski@....de>, lethal@...ux-sh.org,
	linux-fbdev@...r.kernel.org, francis.moro@...il.com,
	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
	Herton Ronaldo Krzesinski <herton@...driva.com.br>,
	stable@...nel.org
Subject: [PATCH] fb: sh-mobile: Fix deadlock risk between lock_fb_info() and
 console_lock()

Following on Herton's patch "fb: avoid possible deadlock caused by
fb_set_suspend" which moves lock_fb_info() out of fb_set_suspend()
to its callers, correct sh-mobile's locking around call to
fb_set_suspend() and the same sort of deaklocks with console_lock()
due to order of taking the lock.

console_lock() must be taken while fb_info is already locked and fb_info
must be locked while calling fb_set_suspend().

Signed-off-by: Bruno Prémont <bonbons@...ux-vserver.org>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@....de>
---

Hi Florian,

> On the other hand I just noticed the original patch didn't have
> Bruno's Signed-off and a commit message was missing. So may I ask you,
> Bruno, to add your Signed-off or preferably resend the version tested
> by Guennadi in the appropriate patch format.

Here it is with commit message and the Signed-off-by's.

Thanks,
Bruno




 drivers/video/sh_mobile_hdmi.c |   47 ++++++++++++++++++++++-----------------
 1 files changed, 26 insertions(+), 21 deletions(-)

diff --git a/drivers/video/sh_mobile_hdmi.c b/drivers/video/sh_mobile_hdmi.c
index 7d54e2c..647ba98 100644
--- a/drivers/video/sh_mobile_hdmi.c
+++ b/drivers/video/sh_mobile_hdmi.c
@@ -1111,6 +1111,7 @@ static long sh_hdmi_clk_configure(struct sh_hdmi *hdmi, unsigned long hdmi_rate,
 static void sh_hdmi_edid_work_fn(struct work_struct *work)
 {
 	struct sh_hdmi *hdmi = container_of(work, struct sh_hdmi, edid_work.work);
+	struct fb_info *info;
 	struct sh_mobile_hdmi_info *pdata = hdmi->dev->platform_data;
 	struct sh_mobile_lcdc_chan *ch;
 	int ret;
@@ -1123,8 +1124,9 @@ static void sh_hdmi_edid_work_fn(struct work_struct *work)
 
 	mutex_lock(&hdmi->mutex);
 
+	info = hdmi->info;
+
 	if (hdmi->hp_state == HDMI_HOTPLUG_CONNECTED) {
-		struct fb_info *info = hdmi->info;
 		unsigned long parent_rate = 0, hdmi_rate;
 
 		ret = sh_hdmi_read_edid(hdmi, &hdmi_rate, &parent_rate);
@@ -1148,42 +1150,45 @@ static void sh_hdmi_edid_work_fn(struct work_struct *work)
 
 		ch = info->par;
 
-		console_lock();
+		if (lock_fb_info(info)) {
+			console_lock();
 
-		/* HDMI plug in */
-		if (!sh_hdmi_must_reconfigure(hdmi) &&
-		    info->state == FBINFO_STATE_RUNNING) {
-			/*
-			 * First activation with the default monitor - just turn
-			 * on, if we run a resume here, the logo disappears
-			 */
-			if (lock_fb_info(info)) {
+			/* HDMI plug in */
+			if (!sh_hdmi_must_reconfigure(hdmi) &&
+			    info->state == FBINFO_STATE_RUNNING) {
+				/*
+				 * First activation with the default monitor - just turn
+				 * on, if we run a resume here, the logo disappears
+				 */
 				info->var.width = hdmi->var.width;
 				info->var.height = hdmi->var.height;
 				sh_hdmi_display_on(hdmi, info);
-				unlock_fb_info(info);
+			} else {
+				/* New monitor or have to wake up */
+				fb_set_suspend(info, 0);
 			}
-		} else {
-			/* New monitor or have to wake up */
-			fb_set_suspend(info, 0);
-		}
 
-		console_unlock();
+			console_unlock();
+			unlock_fb_info(info);
+		}
 	} else {
 		ret = 0;
-		if (!hdmi->info)
+		if (!info)
 			goto out;
 
 		hdmi->monspec.modedb_len = 0;
 		fb_destroy_modedb(hdmi->monspec.modedb);
 		hdmi->monspec.modedb = NULL;
 
-		console_lock();
+		if (lock_fb_info(info)) {
+			console_lock();
 
-		/* HDMI disconnect */
-		fb_set_suspend(hdmi->info, 1);
+			/* HDMI disconnect */
+			fb_set_suspend(info, 1);
 
-		console_unlock();
+			console_unlock();
+			unlock_fb_info(info);
+		}
 	}
 
 out:
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/