ip: reassembly: avoid corruption in vnet buffer

Avoid corrupt next_index in vnet_buffer by moving input and output
variables into different memory places instead of sharing a common
space.

Type: fix
Fixes: de34c35fc73226943538149fae9dbc5cfbdc6e75

Change-Id: I34471fc6d0c8487535fac21349e688f398934f6d
Signed-off-by: Klement Sekera <ksekera@cisco.com>

diff --git a/src/vnet/buffer.h b/src/vnet/buffer.h
index d160ae8..aed72c5 100644 (file)
--- a/src/vnet/buffer.h
+++ b/src/vnet/buffer.h
@@ -185,8 +185,9 @@ typedef struct
        /* reassembly */
        union
        {
-         /* group input/handoff as handoff is done before input is consumed,
-          * this way we can handoff while keeping input variables intact */
+         /* group input/output/handoff to simplify the code, this way:
+          * we can handoff while keeping input variables intact
+          * and also we can write the output and still use next_index later */
          struct
          {
            /* input variables */
@@ -200,23 +201,23 @@ typedef struct
            {
              u16 owner_thread_index;
            };
-         };
-         /* output variables */
-         struct
-         {
-           union
+           /* output variables */
+           struct
            {
-             /* shallow virtual reassembly output variables */
-             struct
-             {
-               u8 ip_proto;    /* protocol in ip header */
-               u16 l4_src_port;        /* tcp/udp/icmp src port */
-               u16 l4_dst_port;        /* tcp/udp/icmp dst port */
-             };
-             /* full reassembly output variables */
-             struct
+             union
              {
-               u16 estimated_mtu;      /* estimated MTU calculated during reassembly */
+               /* shallow virtual reassembly output variables */
+               struct
+               {
+                 u8 ip_proto;  /* protocol in ip header */
+                 u16 l4_src_port;      /* tcp/udp/icmp src port */
+                 u16 l4_dst_port;      /* tcp/udp/icmp dst port */
+               };
+               /* full reassembly output variables */
+               struct
+               {
+                 u16 estimated_mtu;    /* estimated MTU calculated during reassembly */
+               };
              };
            };
          };