[PATCH] USB: gadgetfs: do not WARN about excessively large memory allocations

[Zi Yan]

GadgetFS passes an excessively large user input len to kmalloc and kmalloc
gives a WARN (see below for details). Suppress it by passing __GFP_NOWARN
to kmalloc used by both ep_write_iter() and ep_read_iter(). Follow the same
method as commit 4f2629ea67e72 ("USB: usbfs: Don't WARN about excessively
large memory allocations").

kmalloc is used to allocate physically contiguous memory for kernel
allocations. For requests larger than KMALLOC_MAX_CACHE_SIZE, kmalloc uses
the page allocator and can only support up to KMALLOC_MAX_SIZE. For request
sizes bigger than KMALLOC_MAX_SIZE, the page allocator can emit a WARN
because kmalloc allocates an order greater than MAX_PAGE_ORDER.

Fixes: b3c466ce5129 ("page allocator: do not sanity check order in the fast=
 path")
Reported-by: syzbot+805630f1453e490427fa@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/all/6a820ebc.9ebadd4d.20b15e.001b.GAE@googl=
e.com/
Tested-by: syzbot+805630f1453e490427fa@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
 drivers/usb/gadget/legacy/inode.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/=
inode.c
index d87a8ab515107..278a0a2b39f4c 100644
--- a/drivers/usb/gadget/legacy/inode.c
+++ b/drivers/usb/gadget/legacy/inode.c
@@ -604,7 +604,7 @@ ep_read_iter(struct kiocb *iocb, struct iov_iter *to)
 		return -EBADMSG;
 	}
=20
-	buf =3D kmalloc(len, GFP_KERNEL);
+	buf =3D kmalloc(len, GFP_KERNEL | __GFP_NOWARN);
 	if (unlikely(!buf)) {
 		mutex_unlock(&epdata->lock);
 		return -ENOMEM;
@@ -666,7 +666,7 @@ ep_write_iter(struct kiocb *iocb, struct iov_iter *from=
)
 		return -EBADMSG;
 	}
=20
-	buf =3D kmalloc(len, GFP_KERNEL);
+	buf =3D kmalloc(len, GFP_KERNEL | __GFP_NOWARN);
 	if (unlikely(!buf)) {
 		mutex_unlock(&epdata->lock);
 		return -ENOMEM;
--=20
2.53.0






--=20
Best Regards,
Yan, Zi