linux-hardening - [PATCH][next] usb: host: ehci-sched: Use struct

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Date:   Tue, 11 Jan 2022 01:54:27 -0600
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Alan Stern <stern@...land.harvard.edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        linux-hardening@...r.kernel.org
Subject: [PATCH][next] usb: host: ehci-sched: Use struct_size() in kzalloc()

Make use of the struct_size() helper instead of an open-coded version,
in order to avoid any potential type mistakes or integer overflows that,
in the worse scenario, could lead to heap overflows.

Also, address the following sparse warning:
drivers/usb/host/ehci-sched.c:1168:40: warning: using sizeof on a flexible structure

Link: https://github.com/KSPP/linux/issues/160
Link: https://github.com/KSPP/linux/issues/174
Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---
 drivers/usb/host/ehci-sched.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 0f85aa9b2fb1..bd542b6fc46b 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1165,10 +1165,8 @@ static struct ehci_iso_sched *
 iso_sched_alloc(unsigned packets, gfp_t mem_flags)
 {
 	struct ehci_iso_sched	*iso_sched;
-	int			size = sizeof(*iso_sched);
 
-	size += packets * sizeof(struct ehci_iso_packet);
-	iso_sched = kzalloc(size, mem_flags);
+	iso_sched = kzalloc(struct_size(iso_sched, packet, packets), mem_flags);
 	if (likely(iso_sched != NULL))
 		INIT_LIST_HEAD(&iso_sched->td_list);
 
-- 
2.27.0