[PATCH 5.10 052/157] net/qrtr: fix __netdev_alloc_skb call

Greg Kroah-Hartman
2021-03-22T12:44:01Z

From: Pavel Skripkin <paskripkin@gmail.com>

commit 093b036aa94e01a0bea31a38d7f0ee28a2749023 upstream.

syzbot found WARNING in __alloc_pages_nodemask()[1] when order >= MAX_ORDER.
It was caused by a huge length value passed from userspace to qrtr_tun_write_iter(),
which tries to allocate skb. Since the value comes from the untrusted source
there is no need to raise a warning in __alloc_pages_nodemask().

[1] WARNING in __alloc_pages_nodemask+0x5f8/0x730 mm/page_alloc.c:5014
Call Trace:
__alloc_pages include/linux/gfp.h:511 [inline]
__alloc_pages_node include/linux/gfp.h:524 [inline]
alloc_pages_node include/linux/gfp.h:538 [inline]
kmalloc_large_node+0x60/0x110 mm/slub.c:3999
__kmalloc_node_track_caller+0x319/0x3f0 mm/slub.c:4496
__kmalloc_reserve net/core/skbuff.c:150 [inline]
__alloc_skb+0x4e4/0x5a0 net/core/skbuff.c:210
__netdev_alloc_skb+0x70/0x400 net/core/skbuff.c:446
netdev_alloc_skb include/linux/skbuff.h:2832 [inline]
qrtr_endpoint_post+0x84/0x11b0 net/qrtr/qrtr.c:442
qrtr_tun_write_iter+0x11f/0x1a0 net/qrtr/tun.c:98
call_write_iter include/linux/fs.h:1901 [inline]
new_sync_write+0x426/0x650 fs/read_write.c:518
vfs_write+0x791/0xa30 fs/read_write.c:605
ksys_write+0x12d/0x250 fs/read_write.c:658
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported-by: syzbot+80dccaee7c6630fa9dcf@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Acked-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/qrtr/qrtr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/qrtr/qrtr.c
+++ b/net/qrtr/qrtr.c
@@ -433,7 +433,7 @@ int qrtr_endpoint_post(struct qrtr_endpo
if (len == 0 || len & 3)
return -EINVAL;

- skb = netdev_alloc_skb(NULL, len);
+ skb = __netdev_alloc_skb(NULL, len, GFP_ATOMIC | __GFP_NOWARN);
if (!skb)
return -ENOMEM;