Re: Possible leaks in network drivers

[Randy.Dunlap]

On Wed, 21 Jun 2006 18:28:37 +0200 Eric Sesterhenn wrote:

> hi,
> 
> Coverity complains about several pretty similar resource leaks
> inside the net drivers, and i am not sure if those are real

Linux network driver development is done on the netdev
mailing list (netdev@xxxxxxxxxxxxxxx).
You'll find a larger pool of the right people there...


> name				coverity #id
> 
> drivers/net/8390.c		623
> drivers/net/pcmcia/xirc2ps_cs.c	627
> drivers/net/sis190.c		628
> drivers/net/wireless/wavelan.c	634
> drivers/net/wireless/orinoco.c	661
> drivers/net/depca.c		1246
> drivers/net/hp100.c		1247
> drivers/net/smc9194.c		1248
> drivers/net/skge.c		1249
> 
> Its always in the hard_start_xmit() function
> of the driver. Where we call skb=skb_padto(skb, ETH_ZLEN),
> and dont free the skb later when something goes wrong.
> 
> Here is the output from the sis190.c case:
> 
> ------------snip--8<-------------
> 1158 		if (unlikely(skb->len < ETH_ZLEN)) {
> 
> Event alloc_fn: Called allocation function "skb_padto" [model]
> Event var_assign: Assigned variable "skb" to storage returned from "skb_padto"
> Also see events: [var_assign][leaked_storage]
> 
> 1159 			skb = skb_padto(skb, ETH_ZLEN);
> 
> At conditional (1): "skb == 0" taking false path
> 
> 1160 			if (!skb) {
> 1161 				tp->stats.tx_dropped++;
> 1162 				goto out;
> 1163 			}
> 1164 			len = ETH_ZLEN;
> 1165 		} else {
> 1166 			len = skb->len;
> 1167 		}
> 1168 	
> 1169 		entry = tp->cur_tx % NUM_TX_DESC;
> 1170 		desc = tp->TxDescRing + entry;
> 1171 	
> 
> At conditional (2): "(desc)->status & 2147483648 != 0" taking true path
> 
> 1172 		if (unlikely(le32_to_cpu(desc->status) & OWNbit)) {
> 1173 			netif_stop_queue(dev);
> 
> At conditional (3): "(tp)->msg_enable & 128 != 0" taking true path
> 
> 1174 			net_tx_err(tp, KERN_ERR PFX
> 1175 				   "%s: BUG! Tx Ring full when queue awake!\n",
> 1176 				   dev->name);
> 
> Event leaked_storage: Returned without freeing storage "skb"
> Also see events: [alloc_fn][var_assign]
> 
> 1177 			return NETDEV_TX_BUSY;
> 1178 		}
> 
> ------------snip--8<-------------
> 
> As far as i can see, skb_put() might return a fresh allocated skb, 
> so adding a kfree_skb() here should fix these, or am i missing
> something?
> 
> Thanks Eric

---
~Randy
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