| Message ID | 4fabc166.9208cc0a.4de8.ffff9211@mx.google.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
On Thu, 2012-05-10 at 17:22 +0400, alex.bluesman.smirnov@gmail.com wrote: > From: Alexander Smirnov <alex.bluesman.smirnov@gmail.com> > > Add pskb_may_pull() call when fetching u8 from skb. > > Signed-off-by: Alexander Smirnov <alex.bluesman.smirnov@gmail.com> > --- > net/ieee802154/6lowpan.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c > index 32eb417..0ab3efe 100644 > --- a/net/ieee802154/6lowpan.c > +++ b/net/ieee802154/6lowpan.c > @@ -295,6 +295,8 @@ static u8 lowpan_fetch_skb_u8(struct sk_buff *skb) > { > u8 ret; > > + BUG_ON(!pskb_may_pull(skb, 1)); > + > ret = skb->data[0]; > skb_pull(skb, 1); > No, you cant do that. pskb_may_pull() can fail, and you crash your machine instead of graceful error reporting. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Eric, 2012/5/10 Eric Dumazet <eric.dumazet@gmail.com>: > On Thu, 2012-05-10 at 17:22 +0400, alex.bluesman.smirnov@gmail.com > wrote: >> From: Alexander Smirnov <alex.bluesman.smirnov@gmail.com> >> >> Add pskb_may_pull() call when fetching u8 from skb. >> >> Signed-off-by: Alexander Smirnov <alex.bluesman.smirnov@gmail.com> >> --- >> net/ieee802154/6lowpan.c | 2 ++ >> 1 files changed, 2 insertions(+), 0 deletions(-) >> >> diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c >> index 32eb417..0ab3efe 100644 >> --- a/net/ieee802154/6lowpan.c >> +++ b/net/ieee802154/6lowpan.c >> @@ -295,6 +295,8 @@ static u8 lowpan_fetch_skb_u8(struct sk_buff *skb) >> { >> u8 ret; >> >> + BUG_ON(!pskb_may_pull(skb, 1)); >> + >> ret = skb->data[0]; >> skb_pull(skb, 1); >> > > No, you cant do that. > > pskb_may_pull() can fail, and you crash your machine instead of graceful > error reporting. > thanks for the comment! Using BUG() macro I just want to indicate that something in the bottom of the stack went terribly wrong and you must check your code for bugs.. > > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Alexander Smirnov <alex.bluesman.smirnov@gmail.com> Date: Thu, 10 May 2012 18:05:46 +0400 > Using BUG() macro I just want to indicate that something in the bottom > of the stack went terribly wrong and you must check your code for > bugs.. Then you should do something like: if (WARN_ON_ONCE(!pskb_may_pull(...))) { appropriate_error_handling(); return; } instead. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c index 32eb417..0ab3efe 100644 --- a/net/ieee802154/6lowpan.c +++ b/net/ieee802154/6lowpan.c @@ -295,6 +295,8 @@ static u8 lowpan_fetch_skb_u8(struct sk_buff *skb) { u8 ret; + BUG_ON(!pskb_may_pull(skb, 1)); + ret = skb->data[0]; skb_pull(skb, 1);