skb_linearize(skb) possibly rearranges the skb internal data and then changes the skb->data pointer value. For this reason any other pointer in the code that was assigned skb->data before invoking skb_linearise(skb) must be re-assigned.
In the current tt_query message handling code this is not done and therefore, in case of skb linearization, the pointer used to handle the packet header ends up in pointing to poisoned memory. The packet is then dropped but the translation-table mechanism is corrupted.
Signed-off-by: Antonio Quartulli ordex@autistici.org ---
*** this patch is an important fix and it is for maint ***
routing.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/routing.c b/routing.c index be068f3..b79e42e 100644 --- a/routing.c +++ b/routing.c @@ -638,6 +638,8 @@ int batadv_recv_tt_query(struct sk_buff *skb, struct batadv_hard_iface *recv_if) */ if (skb_linearize(skb) < 0) goto out; + /* skb_linearize() possibly changed skb->data */ + tt_query = (struct batadv_tt_query_packet *)skb->data;
tt_size = batadv_tt_len(ntohs(tt_query->tt_data));
On Thursday 14 June 2012 22:21:28 Antonio Quartulli wrote:
skb_linearize(skb) possibly rearranges the skb internal data and then changes the skb->data pointer value. For this reason any other pointer in the code that was assigned skb->data before invoking skb_linearise(skb) must be re-assigned.
In the current tt_query message handling code this is not done and therefore, in case of skb linearization, the pointer used to handle the packet header ends up in pointing to poisoned memory. The packet is then dropped but the translation-table mechanism is corrupted.
Signed-off-by: Antonio Quartulli ordex@autistici.org
*** this patch is an important fix and it is for maint ***
Don't forget to add
Cc: stable stable@vger.kernel.org
to the patch and a small explanation since when the bug is there (I guess v3.1) and that it may lead to crashes and not only poisened memory (that is the best case.. but maybe the page was removed and we end up in hell when accessing the memory region).
Kind regards, Sven
On Fri, Jun 15, 2012 at 01:45:11PM +0200, Sven Eckelmann wrote:
On Thursday 14 June 2012 22:21:28 Antonio Quartulli wrote:
skb_linearize(skb) possibly rearranges the skb internal data and then changes the skb->data pointer value. For this reason any other pointer in the code that was assigned skb->data before invoking skb_linearise(skb) must be re-assigned.
In the current tt_query message handling code this is not done and therefore, in case of skb linearization, the pointer used to handle the packet header ends up in pointing to poisoned memory. The packet is then dropped but the translation-table mechanism is corrupted.
Signed-off-by: Antonio Quartulli ordex@autistici.org
*** this patch is an important fix and it is for maint ***
Don't forget to add
Cc: stable stable@vger.kernel.org
to the patch and a small explanation since when the bug is there (I guess v3.1) and that it may lead to crashes and not only poisened memory (that is the best case.. but maybe the page was removed and we end up in hell when accessing the memory region).
Hi Sven,
Thank you for your suggestions. Sure, I will.
Regards,
On Friday, June 15, 2012 04:21:28 Antonio Quartulli wrote:
skb_linearize(skb) possibly rearranges the skb internal data and then changes the skb->data pointer value. For this reason any other pointer in the code that was assigned skb->data before invoking skb_linearise(skb) must be re-assigned.
In the current tt_query message handling code this is not done and therefore, in case of skb linearization, the pointer used to handle the packet header ends up in pointing to poisoned memory. The packet is then dropped but the translation-table mechanism is corrupted.
Signed-off-by: Antonio Quartulli ordex@autistici.org
*** this patch is an important fix and it is for maint ***
Next time you send a patch for maint, please be sure the patch is actually based on maint. Your patch does not even apply on top of maint ...
Applied in revision c7d05ee.
Thanks, Marek
b.a.t.m.a.n@lists.open-mesh.org
-
Antonio Quartulli -
Marek Lindner -
Sven Eckelmann