[PATCH] drivers/gpu/vga: use __GFP_NOWARN for user-controlled kmalloc
From: Dmitry Vyukov
Date: Thu Feb 04 2016 - 10:50:03 EST
Size of kmalloc() in vga_arb_write() is controlled by user.
Too large kmalloc() size triggers WARNING message on console.
Use GFP_USER | __GFP_NOWARN for this kmalloc() to not scare admins.
Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
---
Example WARNING:
WARNING: CPU: 2 PID: 29322 at mm/page_alloc.c:2999
__alloc_pages_nodemask+0x7d2/0x1760()
Modules linked in:
CPU: 2 PID: 29322 Comm: syz-executor Tainted: G B 4.5.0-rc1+ #283
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
00000000ffffffff ffff880069eff670 ffffffff8299a06d 0000000000000000
ffff8800658a4740 ffffffff864985a0 ffff880069eff6b0 ffffffff8134fcf9
ffffffff8166de32 ffffffff864985a0 0000000000000bb7 00000000024040c0
Call Trace:
[< inline >] __dump_stack lib/dump_stack.c:15
[<ffffffff8299a06d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
[<ffffffff8134fcf9>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482
[<ffffffff8134ff29>] warn_slowpath_null+0x29/0x30 kernel/panic.c:515
[< inline >] __alloc_pages_slowpath mm/page_alloc.c:2999
[<ffffffff8166de32>] __alloc_pages_nodemask+0x7d2/0x1760 mm/page_alloc.c:3253
[<ffffffff81745c99>] alloc_pages_current+0xe9/0x450 mm/mempolicy.c:2090
[< inline >] alloc_pages include/linux/gfp.h:459
[<ffffffff81669bb6>] alloc_kmem_pages+0x16/0x100 mm/page_alloc.c:3433
[<ffffffff816c20af>] kmalloc_order+0x1f/0x80 mm/slab_common.c:1008
[<ffffffff816c212f>] kmalloc_order_trace+0x1f/0x140 mm/slab_common.c:1019
[< inline >] kmalloc_large include/linux/slab.h:395
[<ffffffff81756b24>] __kmalloc+0x2f4/0x340 mm/slub.c:3557
[< inline >] kmalloc include/linux/slab.h:468
[<ffffffff832c65a4>] vga_arb_write+0xd4/0xe40 drivers/gpu/vga/vgaarb.c:926
[<ffffffff817a9831>] do_loop_readv_writev+0x141/0x1e0 fs/read_write.c:719
[<ffffffff817ad698>] do_readv_writev+0x5f8/0x6e0 fs/read_write.c:849
[<ffffffff817ad8b6>] vfs_writev+0x86/0xc0 fs/read_write.c:886
[< inline >] SYSC_writev fs/read_write.c:919
[<ffffffff817b0a21>] SyS_writev+0x111/0x2b0 fs/read_write.c:911
[<ffffffff86359636>] entry_SYSCALL_64_fastpath+0x16/0x7a
arch/x86/entry/entry_64.S:185
---
drivers/gpu/vga/vgaarb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index f17cb04..d73b85b 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c
@@ -923,7 +923,7 @@ static ssize_t vga_arb_write(struct file *file, const char __user *buf,
int i;
- kbuf = kmalloc(count + 1, GFP_KERNEL);
+ kbuf = kmalloc(count + 1, GFP_USER | __GFP_NOWARN);
if (!kbuf)
return -ENOMEM;
--
2.7.0.rc3.207.g0ac5344