Re: [PATCH linux-next] video: fbdev: fbmem: fix pointer reference to null device field
From: "Paul E. McKenney" <paulmck@kernel.org>
Date: 2022-02-11 01:26:27
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dri-devel, lkml, rcu
On Thu, Feb 10, 2022 at 02:58:24PM +0800, Zhouyi Zhou wrote:
In function do_remove_conflicting_framebuffers, if device is NULL, there will be null pointer reference. The patch add a check to the if expression. Signed-off-by: Zhouyi Zhou <redacted> --- Dear Linux folks I discover this bug in the PowerPC VM provided by Open source lab of Oregon State University: https://lkml.org/lkml/2022/2/8/1145 I found that the root cause of null device field is in offb_init_fb: info = framebuffer_alloc(sizeof(u32) * 16, NULL); I have tested the patch in the PowerPC VM. Hope my patch can be correct.
This looks plausible to me, but I am quite unfamiliar with this code. Thanx, Paul
quoted hunk ↗ jump to hunk
Many Thanks Zhouyi -- drivers/video/fbdev/core/fbmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 34d6bb1bf82e..422b1fc01722 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c@@ -1579,7 +1579,7 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a, * If it's not a platform device, at least print a warning. A * fix would add code to remove the device from the system. */ - if (dev_is_platform(device)) { + if (device && dev_is_platform(device)) { registered_fb[i]->forced_out = true; platform_device_unregister(to_platform_device(device)); } else {-- 2.25.1