net/qrtr: restrict user-controlled length in qrtr_tun_write_iter()

syzbot found WARNING in qrtr_tun_write_iter [1] when write_iter length exceeds KMALLOC_MAX_SIZE causing order >= MAX_ORDER condition. Additionally, there is no check for 0 length write. [1] WARNING: mm/page_alloc.c:5011 [..] Call Trace: alloc_pages_current+0x18c/0x2a0 mm/mempolicy.c:2267 alloc_pages include/linux/gfp.h:547 [inline] kmalloc_order+0x2e/0xb0 mm/slab_common.c:837 kmalloc_order_trace+0x14/0x120 mm/slab_common.c:853 kmalloc include/linux/slab.h:557 [inline] kzalloc include/linux/slab.h:682 [inline] qrtr_tun_write_iter+0x8a/0x180 net/qrtr/tun.c:83 call_write_iter include/linux/fs.h:1901 [inline] Reported-by: [email protected] Signed-off-by: Sabyrzhan Tasbolatov <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jakub Kicinski <[email protected]>
chewitt · Feb 4, 2021 · 2a80c15 · 2a80c15
1 parent a4dc7ee
commit 2a80c15
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/net/qrtr/tun.c b/net/qrtr/tun.c
@@ -80,6 +80,12 @@ static ssize_t qrtr_tun_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	ssize_t ret;
 	void *kbuf;
 
+	if (!len)
+		return -EINVAL;
+
+	if (len > KMALLOC_MAX_SIZE)
+		return -ENOMEM;
+
 	kbuf = kzalloc(len, GFP_KERNEL);
 	if (!kbuf)
 		return -ENOMEM;