fbcon: check return value of con2fb_acquire_newinfo()

[ Upstream commit 011a050 ]

If fbcon_open() fails when called from con2fb_acquire_newinfo() then
info->fbcon_par pointer remains NULL which is later dereferenced.

Add check for return value of the function con2fb_acquire_newinfo() to
avoid it.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: d1baa4f ("fbcon: set_con2fb_map fixes")
Cc: stable@vger.kernel.org
Signed-off-by: Andrey Vatoropin <a.vatoropin@crpt.ru>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Andrey Vatoropin

drivers/video/fbdev/core/fbcon.c

@@ -1068,7 +1068,8 @@ static void fbcon_init(struct vc_data *vc, bool init)
 		return;
 
 	if (!info->fbcon_par)
-		con2fb_acquire_newinfo(vc, info, vc->vc_num);
+		if (con2fb_acquire_newinfo(vc, info, vc->vc_num))
+			return;
 
 	/* If we are not the first console on this
 	   fb, copy the font from that console */