netdev - Re: [PATCH RFC] solos-pci: Fix BUG() with shared skb

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 04 Sep 2013 21:41:15 +0100
From:	David Woodhouse <dwmw2@...radead.org>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, simon@...e.lp0.eu,
	linux-atm-general@...ts.sourceforge.net, nathan@...verse.com.au
Subject: Re: [PATCH RFC] solos-pci: Fix BUG() with shared skb

On Wed, 2013-09-04 at 14:30 -0400, David Miller wrote:
> skb_realloc_headroom() should do everything you need.

Great, thanks! Something like this then... ? 

Do I really need the truesize check? And if so, is there a better way to
handle the ATM accounting? It just *happens* to be the case that the the
br2684_pop() and pppoatm_pop() functions don't mind being bypassed in
this fashion, and we should probably get away with tweaking the core ATM
accounting directly like this. Doesn't make me happy though...

diff --git a/drivers/atm/solos-pci.c b/drivers/atm/solos-pci.c
index 32784d1..4492c0f 100644
--- a/drivers/atm/solos-pci.c
+++ b/drivers/atm/solos-pci.c
@@ -1145,19 +1145,19 @@ static int psend(struct atm_vcc *vcc, struct sk_buff *skb)
 		return 0;
 	}
 
-	if (!skb_clone_writable(skb, sizeof(*header))) {
-		int expand_by = 0;
-		int ret;
-
-		if (skb_headroom(skb) < sizeof(*header))
-			expand_by = sizeof(*header) - skb_headroom(skb);
-
-		ret = pskb_expand_head(skb, expand_by, 0, GFP_ATOMIC);
-		if (ret) {
-			dev_warn(&card->dev->dev, "pskb_expand_head failed.\n");
-			solos_pop(vcc, skb);
-			return ret;
-		}
+	if (skb_headroom(skb) < sizeof(*header)) {
+		struct sk_buff *nskb;
+
+		nskb = skb_realloc_headroom(skb, sizeof(*header));
+		if (!nskb) {
+			solos_pop(vcc, skb);
+			return -ENOMEM;
+		}
+		if (skb->truesize != nskb->truesize)
+			atm_force_charge(vcc, nskb->truesize - skb->truesize);
+ 
+		dev_kfree_skb_any(skb);
+		skb = nskb;
 	}
 
 	header = (void *)skb_push(skb, sizeof(*header));


-- 
dwmw2


Download attachment "smime.p7s" of type "application/x-pkcs7-signature" (5745 bytes)