2015-02-17 10:34:15

by Alexander Drozdov

Subject: [PATCH] ipv4: ip_check_defrag should correctly check return value of skb_copy_bits

skb_copy_bits() returns zero on success and negative value on error,
so it is needed to invert the condition in ip_check_defrag().

Fixes: 1bf3751ec90c ("ipv4: ip_check_defrag must not modify skb before unsharing")
Signed-off-by: Alexander Drozdov <[email protected]>
---
net/ipv4/ip_fragment.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index e5b6d0d..2c8d98e 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -664,7 +664,7 @@ struct sk_buff *ip_check_defrag(struct sk_buff *skb, u32 user)
if (skb->protocol != htons(ETH_P_IP))
return skb;

- if (!skb_copy_bits(skb, 0, &iph, sizeof(iph)))
+ if (skb_copy_bits(skb, 0, &iph, sizeof(iph)) < 0)
return skb;

if (iph.ihl < 5 || iph.version != 4)
--
1.9.1

2015-02-17 13:33:49

by Denis Kirjanov

Subject: Re: [PATCH] ipv4: ip_check_defrag should correctly check return value of skb_copy_bits

On 2/17/15, Alexander Drozdov <[email protected]> wrote:
> skb_copy_bits() returns zero on success and negative value on error,
> so it is needed to invert the condition in ip_check_defrag().
>

Nice. Grepping through the net directory shows that the skb_copy_bits()
return value is completely ignored in net/wireless/util.c


> Fixes: 1bf3751ec90c ("ipv4: ip_check_defrag must not modify skb before
> unsharing")
> Signed-off-by: Alexander Drozdov <[email protected]>
> ---
> net/ipv4/ip_fragment.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
> index e5b6d0d..2c8d98e 100644
> --- a/net/ipv4/ip_fragment.c
> +++ b/net/ipv4/ip_fragment.c
> @@ -664,7 +664,7 @@ struct sk_buff *ip_check_defrag(struct sk_buff *skb, u32
> user)
> if (skb->protocol != htons(ETH_P_IP))
> return skb;
>
> - if (!skb_copy_bits(skb, 0, &iph, sizeof(iph)))
> + if (skb_copy_bits(skb, 0, &iph, sizeof(iph)) < 0)
> return skb;
>
> if (iph.ihl < 5 || iph.version != 4)
> --
> 1.9.1
>
> --
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2015-02-17 15:55:35

by Eric Dumazet

Subject: Re: [PATCH] ipv4: ip_check_defrag should correctly check return value of skb_copy_bits

On Tue, 2015-02-17 at 13:33 +0300, Alexander Drozdov wrote:
> skb_copy_bits() returns zero on success and negative value on error,
> so it is needed to invert the condition in ip_check_defrag().
>
> Fixes: 1bf3751ec90c ("ipv4: ip_check_defrag must not modify skb before unsharing")
> Signed-off-by: Alexander Drozdov <[email protected]>
> ---
> net/ipv4/ip_fragment.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
> index e5b6d0d..2c8d98e 100644
> --- a/net/ipv4/ip_fragment.c
> +++ b/net/ipv4/ip_fragment.c
> @@ -664,7 +664,7 @@ struct sk_buff *ip_check_defrag(struct sk_buff *skb, u32 user)
> if (skb->protocol != htons(ETH_P_IP))
> return skb;
>
> - if (!skb_copy_bits(skb, 0, &iph, sizeof(iph)))
> + if (skb_copy_bits(skb, 0, &iph, sizeof(iph)) < 0)
> return skb;
>
> if (iph.ihl < 5 || iph.version != 4)

Thanks, I wonder how this was not found/fixed earlier.

Acked-by: Eric Dumazet <[email protected]>
Cc: Johannes Berg <[email protected]>

2015-02-20 20:23:21

by David Miller

Subject: Re: [PATCH] ipv4: ip_check_defrag should correctly check return value of skb_copy_bits

From: Alexander Drozdov <[email protected]>
Date: Tue, 17 Feb 2015 13:33:46 +0300

> skb_copy_bits() returns zero on success and negative value on error,
> so it is needed to invert the condition in ip_check_defrag().
>
> Fixes: 1bf3751ec90c ("ipv4: ip_check_defrag must not modify skb before unsharing")
> Signed-off-by: Alexander Drozdov <[email protected]>

Applied and queued up for -stable, thanks.