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Message-Id: <200706190956.26252.okir@lst.de>
Date: Tue, 19 Jun 2007 09:56:24 +0200
From: Olaf Kirch <okir@....de>
To: netdev@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] net: Make skb_seq_read unmap the last fragment
From: Olaf Kirch <olaf.kirch@...cle.com>
Make skb_seq_read unmap the last fragment
Having walked through the entire skbuff, skb_seq_read would leave the
last fragment mapped. As a consequence, the unwary caller would leak
kmaps, and proceed with preempt_count off by one. The only (kind of
non-intuitive) workaround is to use skb_seq_read_abort.
This patch makes sure skb_seq_read always unmaps frag_data after having
cycled through the skb's paged part.
Signed-off-by: olaf.kirch@...cle.com
---
net/core/skbuff.c | 5 +++++
1 file changed, 5 insertions(+)
Index: build-2.6/net/core/skbuff.c
===================================================================
--- build-2.6.orig/net/core/skbuff.c
+++ build-2.6/net/core/skbuff.c
@@ -1706,6 +1706,11 @@ next_skb:
st->stepped_offset += frag->size;
}
+ if (st->frag_data) {
+ kunmap_skb_frag(st->frag_data);
+ st->frag_data = NULL;
+ }
+
if (st->cur_skb->next) {
st->cur_skb = st->cur_skb->next;
st->frag_idx = 0;
--
Olaf Kirch | --- o --- Nous sommes du soleil we love when we play
okir@....de | / | \ sol.dhoop.naytheet.ah kin.ir.samse.qurax
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