On 13/06/2024 21:27, Ken Milmore wrote:
> On 13/06/2024 18:21, Alexey Khoroshilov wrote:
>> On 13.06.2024 14:30, Greg Kroah-Hartman wrote:
>>> 5.10-stable review patch. If anyone has any objections, please let me know.
>>
>> The patch is cleanly applied to 5.10, but it leads to uninit value
>> access in rtl_tx_slots_avail().
>>
>>
>> unsigned int frags;
>> u32 opts[2];
>>
>> txd_first = tp->TxDescArray + entry;
>>
>> if (unlikely(!rtl_tx_slots_avail(tp, frags))) {
>> ^^^^^ - USE OF UNINIT VALUE
>> if (net_ratelimit())
>> netdev_err(dev, "BUG! Tx Ring full when queue awake!\n");
>> goto err_stop_0;
>> }
>>
>> opts[1] = rtl8169_tx_vlan_tag(skb);
>> opts[0] = 0;
>>
>> if (!rtl_chip_supports_csum_v2(tp))
>> rtl8169_tso_csum_v1(skb, opts);
>> else if (!rtl8169_tso_csum_v2(tp, skb, opts))
>> goto err_dma_0;
>>
>> if (unlikely(rtl8169_tx_map(tp, opts, skb_headlen(skb), skb->data,
>> entry, false)))
>> goto err_dma_0;
>>
>> txd_first = tp->TxDescArray + entry;
>>
>> frags = skb_shinfo(skb)->nr_frags;
>> ^^^^^^ - INITIALIZATION IS HERE AFTER THE PATCH
>>
>> There is no such problem in upstream because rtl_tx_slots_avail() has no
>> nr_frags argument there.
>>
>>
>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>>
>> --
>> Alexey Khoroshilov
>> Linux Verification Center, ISPRAS
>
> Looks like the frags argument was removed in commit 83c317d7b36bb (r8169: remove nr_frags argument from rtl_tx_slots_avail), which first appears in linux-5.11.
>
> I dare say it would be safe to replace
> if (unlikely(!rtl_tx_slots_avail(tp, frags))) {
> with
> if (unlikely(!rtl_tx_slots_avail(tp, MAX_SKB_FRAGS))) {
>
> Best wait for Heiner to confirm though.
Further to this, I have tested the following amended patch to 5.10 on the RTL8125b and it works without problems:
diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index c29d43c5f450..8aa0097bf887 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -4279,16 +4279,16 @@ static void rtl8169_doorbell(struct rtl8169_private *tp)
static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
struct net_device *dev)
{
- unsigned int frags = skb_shinfo(skb)->nr_frags;
struct rtl8169_private *tp = netdev_priv(dev);
unsigned int entry = tp->cur_tx % NUM_TX_DESC;
struct TxDesc *txd_first, *txd_last;
bool stop_queue, door_bell;
+ unsigned int frags;
u32 opts[2];
txd_first = tp->TxDescArray + entry;
- if (unlikely(!rtl_tx_slots_avail(tp, frags))) {
+ if (unlikely(!rtl_tx_slots_avail(tp, MAX_SKB_FRAGS))) {
if (net_ratelimit())
netdev_err(dev, "BUG! Tx Ring full when queue awake!\n");
goto err_stop_0;
@@ -4309,6 +4309,7 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
entry, false)))
goto err_dma_0;
+ frags = skb_shinfo(skb)->nr_frags;
if (frags) {
if (rtl8169_xmit_frags(tp, skb, opts, entry))
goto err_dma_1;
An alternative to this amendment would be to apply 83c317d7b36bb as a prerequisite, but that does not apply cleanly to 5.10 without some massaging.
Because of these complications, I would suggest it may be safest to omit this patch from 5.10 for now.
NAKed-by: Ken Milmore <ken.milmore@xxxxxxxxx>
