From 4f2629ea67e7225c3fd292c7fe4f5b3c9d6392de Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@rowland.harvard.edu>
Date: Tue, 18 May 2021 16:18:35 -0400
Subject: [PATCH] USB: usbfs: Don't WARN about excessively large memory
allocations
Git-commit: 4f2629ea67e7225c3fd292c7fe4f5b3c9d6392de
REferences: bsc#1222004 CVE-2021-47170
Patch-mainline: v5.13-rc4
Syzbot found that the kernel generates a WARNing if the user tries to
submit a bulk transfer through usbfs with a buffer that is way too
large. This isn't a bug in the kernel; it's merely an invalid request
from the user and the usbfs code does handle it correctly.
In theory the same thing can happen with async transfers, or with the
packet descriptor table for isochronous transfers.
To prevent the MM subsystem from complaining about these bad
allocation requests, add the __GFP_NOWARN flag to the kmalloc calls
for these buffers.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Reported-and-tested-by: syzbot+882a85c0c8ec4a3e2281@syzkaller.appspotmail.com
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20210518201835.GA1140918@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
drivers/usb/core/devio.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1206,7 +1206,12 @@ static int proc_bulk(struct usb_dev_stat
ret = usbfs_increase_memory_usage(len1 + sizeof(struct urb));
if (ret)
return ret;
- tbuf = kmalloc(len1, GFP_KERNEL);
+
+ /*
+ * len1 can be almost arbitrarily large. Don't WARN if it's
+ * too big, just fail the request.
+ */
+ tbuf = kmalloc(len1, GFP_KERNEL | __GFP_NOWARN);
if (!tbuf) {
ret = -ENOMEM;
goto done;
@@ -1634,7 +1639,7 @@ static int proc_do_submiturb(struct usb_
if (num_sgs) {
as->urb->sg = kmalloc(num_sgs * sizeof(struct scatterlist),
- GFP_KERNEL);
+ GFP_KERNEL | __GFP_NOWARN);
if (!as->urb->sg) {
ret = -ENOMEM;
goto error;
@@ -1645,7 +1650,7 @@ static int proc_do_submiturb(struct usb_
totlen = uurb->buffer_length;
for (i = 0; i < as->urb->num_sgs; i++) {
u = (totlen > USB_SG_SIZE) ? USB_SG_SIZE : totlen;
- buf = kmalloc(u, GFP_KERNEL);
+ buf = kmalloc(u, GFP_KERNEL | __GFP_NOWARN);
if (!buf) {
ret = -ENOMEM;
goto error;
@@ -1669,7 +1674,7 @@ static int proc_do_submiturb(struct usb_
(uurb_start - as->usbm->vm_start);
} else {
as->urb->transfer_buffer = kmalloc(uurb->buffer_length,
- GFP_KERNEL);
+ GFP_KERNEL | __GFP_NOWARN);
if (!as->urb->transfer_buffer) {
ret = -ENOMEM;
goto error;