[PATCH RESEND] HID: wacom: handle kzalloc() allocation failure in wacom_wac_queue_flush()

[PATCH RESEND] HID: wacom: handle kzalloc() allocation failure in wacom_wac_queue_flush()

[Qasim Ijaz]

During wacom_wac_queue_flush() the code calls
kzalloc() to allocate a zero initialised buffer
which it uses as a storage buffer to get data
from the fifo via kfifo_out(). However it does not
check kzalloc() for allocation failure which returns
NULL and could potentially lead to a NULL deref.

Fix this by checking for kzalloc() failure and skipping
the current entry if allocation failure occurs.

Fixes: 5e013ad20689 ("HID: wacom: Remove static WACOM_PKGLEN_MAX limit")
Reviewed-by: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Qasim Ijaz <qasdev00@gmail.com>
---
 drivers/hid/wacom_sys.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
index 97393a3083ca..666b7eb0fdfe 100644
--- a/drivers/hid/wacom_sys.c
+++ b/drivers/hid/wacom_sys.c
@@ -70,10 +70,16 @@ static void wacom_wac_queue_flush(struct hid_device *hdev,
 {
 	while (!kfifo_is_empty(fifo)) {
 		int size = kfifo_peek_len(fifo);
-		u8 *buf = kzalloc(size, GFP_KERNEL);
+		u8 *buf;
 		unsigned int count;
 		int err;
 
+		buf = kzalloc(size, GFP_KERNEL);
+		if (!buf) {
+			kfifo_skip(fifo);
+			continue;
+		}
+
 		count = kfifo_out(fifo, buf, size);
 		if (count != size) {
 			// Hard to say what is the "right" action in this
-- 
2.39.5

Re: [PATCH RESEND] HID: wacom: handle kzalloc() allocation failure in wacom_wac_queue_flush()

[Markus Elfring]

…
> from the fifo via kfifo_out(). However it does not
> check kzalloc() for allocation failure which returns 
> NULL and could potentially lead to a NULL deref.
…
                                            pointer dereference?

I guess that word wrapping can occasionally become a bit nicer
for text lines which may be longer than 52 characters.

Regards,
Markus