linux-kernel - [PATCH 1/2] staging: android: ion: Add __GFP

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Message-Id: <20180105191409.17807-1-labbott@redhat.com>
Date:   Fri,  5 Jan 2018 11:14:08 -0800
From:   Laura Abbott <labbott@...hat.com>
To:     Greg KH <gregkh@...uxfoundation.org>,
        Sumit Semwal <sumit.semwal@...aro.org>
Cc:     Laura Abbott <labbott@...hat.com>, devel@...verdev.osuosl.org,
        LKML <linux-kernel@...r.kernel.org>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH 1/2] staging: android: ion: Add __GFP_NOWARN for system contig heap

syzbot reported a warning from Ion:

  WARNING: CPU: 1 PID: 3485 at mm/page_alloc.c:3926

  ...
   __alloc_pages_nodemask+0x9fb/0xd80 mm/page_alloc.c:4252
  alloc_pages_current+0xb6/0x1e0 mm/mempolicy.c:2036
  alloc_pages include/linux/gfp.h:492 [inline]
  ion_system_contig_heap_allocate+0x40/0x2c0
  drivers/staging/android/ion/ion_system_heap.c:374
  ion_buffer_create drivers/staging/android/ion/ion.c:93 [inline]
  ion_alloc+0x2c1/0x9e0 drivers/staging/android/ion/ion.c:420
  ion_ioctl+0x26d/0x380 drivers/staging/android/ion/ion-ioctl.c:84
  vfs_ioctl fs/ioctl.c:46 [inline]
  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
  SYSC_ioctl fs/ioctl.c:701 [inline]
  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692

This is a warning about attempting to allocate order > MAX_ORDER. This
is coming from a userspace Ion allocation request. Since userspace is
free to request however much memory it wants (and the kernel is free to
deny its allocation), silence the allocation attempt with __GFP_NOWARN
in case it fails.

Reported-by: syzbot+76e7efc4748495855a4d@...kaller.appspotmail.com
Reported-by: syzbot <syzkaller@...glegroups.com>
Signed-off-by: Laura Abbott <labbott@...hat.com>
---
 drivers/staging/android/ion/ion_system_heap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
index 71c4228f8238..bc19cdd30637 100644
--- a/drivers/staging/android/ion/ion_system_heap.c
+++ b/drivers/staging/android/ion/ion_system_heap.c
@@ -362,7 +362,7 @@ static int ion_system_contig_heap_allocate(struct ion_heap *heap,
 	unsigned long i;
 	int ret;

-	page = alloc_pages(low_order_gfp_flags, order);
+	page = alloc_pages(low_order_gfp_flags | __GFP_NOWARN, order);
 	if (!page)
 		return -ENOMEM;

-- 
2.14.3