net/esp4: Fix invalid esph pointer crash

Both esp_output and esp_xmit take a pointer to the ESP header
and place it in esp_info struct prior to calling esp_output_head.

Inside esp_output_head, the call to esp_output_udp_encap
makes sure to update the pointer if it gets invalid.
However, if esp_output_head itself calls skb_cow_data, the
pointer is not updated and stays invalid, causing a crash
after esp_output_head returns.

Update the pointer if it becomes invalid in esp_output_head

Fixes: fca11ebde3f0 ("esp4: Reorganize esp_output")
Signed-off-by: Ilan Tayari <ilant@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 7f2caf71212beb1b3a65cdf75df38868be21c627..65cc02bd82bc87991a29135a58c059c7916a5a35 100644 (file)
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -317,6 +317,7 @@ cow:
        if (nfrags < 0)
                goto out;
        tail = skb_tail_pointer(trailer);
+       esp->esph = ip_esp_hdr(skb);
 
 skip_cow:
        esp_output_fill_trailer(tail, esp->tfclen, esp->plen, esp->proto);