From 60d1d93664a0bb3d5af722ed38c57ee165a45bf7 Mon Sep 17 00:00:00 2001 From: Parthasarathy Bhuvaragan Date: Thu, 24 Aug 2017 16:31:23 +0200 Subject: [PATCH] tipc: reassign pointers after skb reallocation / linearization In tipc_msg_reverse(), we assign skb attributes to local pointers in stack at startup. This is followed by skb_linearize() and for cloned buffers we perform skb relocation using pskb_expand_head(). Both these methods may update the skb attributes and thus making the pointers incorrect. In this commit, we fix this error by ensuring that the pointers are re-assigned after any of these skb operations. Fixes: 29042e19f2c60 ("tipc: let function tipc_msg_reverse() expand header when needed") Signed-off-by: Parthasarathy Bhuvaragan Reviewed-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/msg.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/tipc/msg.c b/net/tipc/msg.c index dcd90e6fa7c3..6ef379f004ac 100644 --- a/net/tipc/msg.c +++ b/net/tipc/msg.c @@ -479,13 +479,14 @@ bool tipc_msg_make_bundle(struct sk_buff **skb, struct tipc_msg *msg, bool tipc_msg_reverse(u32 own_node, struct sk_buff **skb, int err) { struct sk_buff *_skb = *skb; - struct tipc_msg *hdr = buf_msg(_skb); + struct tipc_msg *hdr; struct tipc_msg ohdr; - int dlen = min_t(uint, msg_data_sz(hdr), MAX_FORWARD_SIZE); + int dlen; if (skb_linearize(_skb)) goto exit; hdr = buf_msg(_skb); + dlen = min_t(uint, msg_data_sz(hdr), MAX_FORWARD_SIZE); if (msg_dest_droppable(hdr)) goto exit; if (msg_errcode(hdr)) @@ -511,6 +512,8 @@ bool tipc_msg_reverse(u32 own_node, struct sk_buff **skb, int err) pskb_expand_head(_skb, BUF_HEADROOM, BUF_TAILROOM, GFP_ATOMIC)) goto exit; + /* reassign after skb header modifications */ + hdr = buf_msg(_skb); /* Now reverse the concerned fields */ msg_set_errcode(hdr, err); msg_set_non_seq(hdr, 0); -- 2.11.0