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Subjectusb: gadget: function: add spinlock for rndis response list
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There's no lock for rndis response list. It could cause list corruption
if two different list_add at the same time like below.
It's better to add in rndis_add_response / rndis_free_response
/ rndis_get_next_response to prevent any race condition on response list.

[ 361.894299] [1: irq/191-dwc3:16979] list_add corruption.
next->prev should be prev (ffffff80651764d0),
but was ffffff883dc36f80. (next=ffffff80651764d0).

[ 361.904380] [1: irq/191-dwc3:16979] Call trace:
[ 361.904391] [1: irq/191-dwc3:16979] __list_add_valid+0x74/0x90
[ 361.904401] [1: irq/191-dwc3:16979] rndis_msg_parser+0x168/0x8c0
[ 361.904409] [1: irq/191-dwc3:16979] rndis_command_complete+0x24/0x84
[ 361.904417] [1: irq/191-dwc3:16979] usb_gadget_giveback_request+0x20/0xe4
[ 361.904426] [1: irq/191-dwc3:16979] dwc3_gadget_giveback+0x44/0x60
[ 361.904434] [1: irq/191-dwc3:16979] dwc3_ep0_complete_data+0x1e8/0x3a0
[ 361.904442] [1: irq/191-dwc3:16979] dwc3_ep0_interrupt+0x29c/0x3dc
[ 361.904450] [1: irq/191-dwc3:16979] dwc3_process_event_entry+0x78/0x6cc
[ 361.904457] [1: irq/191-dwc3:16979] dwc3_process_event_buf+0xa0/0x1ec
[ 361.904465] [1: irq/191-dwc3:16979] dwc3_thread_interrupt+0x34/0x5c

Fixes: f6281af9d62e ("usb: gadget: rndis: use list_for_each_entry_safe")
Signed-off-by: Daehwan Jung <dh10.jung@samsung.com>
---
drivers/usb/gadget/function/rndis.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/usb/gadget/function/rndis.c b/drivers/usb/gadget/function/rndis.c
index b7ccf1803656..b4d58324e2d2 100644
--- a/drivers/usb/gadget/function/rndis.c
+++ b/drivers/usb/gadget/function/rndis.c
@@ -1011,16 +1011,21 @@ void rndis_add_hdr(struct sk_buff *skb)
}
EXPORT_SYMBOL_GPL(rndis_add_hdr);

+/* add spinlock to prevent race condition for rndis response list */
+static DEFINE_SPINLOCK(resp_lock);
+
void rndis_free_response(struct rndis_params *params, u8 *buf)
{
rndis_resp_t *r, *n;

+ spin_lock(&resp_lock);
list_for_each_entry_safe(r, n, &params->resp_queue, list) {
if (r->buf == buf) {
list_del(&r->list);
kfree(r);
}
}
+ spin_unlock(&resp_lock);
}
EXPORT_SYMBOL_GPL(rndis_free_response);

@@ -1030,14 +1035,17 @@ u8 *rndis_get_next_response(struct rndis_params *params, u32 *length)

if (!length) return NULL;

+ spin_lock(&resp_lock);
list_for_each_entry_safe(r, n, &params->resp_queue, list) {
if (!r->send) {
r->send = 1;
*length = r->length;
+ spin_unlock(&resp_lock);
return r->buf;
}
}

+ spin_unlock(&resp_lock);
return NULL;
}
EXPORT_SYMBOL_GPL(rndis_get_next_response);
@@ -1054,7 +1062,9 @@ static rndis_resp_t *rndis_add_response(struct rndis_params *params, u32 length)
r->length = length;
r->send = 0;

+ spin_lock(&resp_lock);
list_add_tail(&r->list, &params->resp_queue);
+ spin_unlock(&resp_lock);
return r;
}

--
2.31.1
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