linux-kernel - [PATCH AUTOSEL 4.4 33/56] fbdev: fix WARNING in __alloc_pages

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Date:   Sat,  1 Jun 2019 09:25:37 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jiufei Xue <jiufei.xue@...ux.alibaba.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Sasha Levin <sashal@...nel.org>,
        dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.4 33/56] fbdev: fix WARNING in __alloc_pages_nodemask bug

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

[ Upstream commit 8c40292be9169a9cbe19aadd1a6fc60cbd1af82f ]

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: Sasha Levin <sashal@...nel.org>
---
 drivers/video/fbdev/core/fbcmap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/video/fbdev/core/fbcmap.c b/drivers/video/fbdev/core/fbcmap.c
index 68a113594808f..2811c4afde01c 100644
--- 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 *cmap, int len, int transp, gfp_t flags)
 	int size = len * sizeof(u16);
 	int ret = -ENOMEM;
 
+	flags |= __GFP_NOWARN;
+
 	if (cmap->len != len) {
 		fb_dealloc_cmap(cmap);
 		if (!len)
-- 
2.20.1