linux-kernel - [PATCH 4.9 015/128] fbdev: fix WARNING in __alloc_pages

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Message-Id: <20190530030437.478216971@linuxfoundation.org>
Date:   Wed, 29 May 2019 20:05:47 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jiufei Xue <jiufei.xue@...ux.alibaba.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: [PATCH 4.9 015/128] fbdev: fix WARNING in __alloc_pages_nodemask bug

From: Jiufei Xue <jiufei.xue@...ux.alibaba.com>

commit 8c40292be9169a9cbe19aadd1a6fc60cbd1af82f upstream.

Syzkaller hit 'WARNING in __alloc_pages_nodemask' bug.

WARNING: CPU: 1 PID: 1473 at mm/page_alloc.c:4377
__alloc_pages_nodemask+0x4da/0x2130
Kernel panic - not syncing: panic_on_warn set ...

Call Trace:
 alloc_pages_current+0xb1/0x1e0
 kmalloc_order+0x1f/0x60
 kmalloc_order_trace+0x1d/0x120
 fb_alloc_cmap_gfp+0x85/0x2b0
 fb_set_user_cmap+0xff/0x370
 do_fb_ioctl+0x949/0xa20
 fb_ioctl+0xdd/0x120
 do_vfs_ioctl+0x186/0x1070
 ksys_ioctl+0x89/0xa0
 __x64_sys_ioctl+0x74/0xb0
 do_syscall_64+0xc8/0x550
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

This is a warning about order >= MAX_ORDER and the order is from
userspace ioctl. Add flag __NOWARN to silence this warning.

Signed-off-by: Jiufei Xue <jiufei.xue@...ux.alibaba.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/video/fbdev/core/fbcmap.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/video/fbdev/core/fbcmap.c
+++ b/drivers/video/fbdev/core/fbcmap.c
@@ -94,6 +94,8 @@ int fb_alloc_cmap_gfp(struct fb_cmap *cm
 	int size = len * sizeof(u16);
 	int ret = -ENOMEM;
 
+	flags |= __GFP_NOWARN;
+
 	if (cmap->len != len) {
 		fb_dealloc_cmap(cmap);
 		if (!len)