power: fix sanity checks for guest channel read

In function power_guest_channel_read_msg, 'lcore_id' is used before
validity check, which may cause buffer 'global_fds' accessed by index
'lcore_id' overflow.

This patch moves the validity check of 'lcore_id' before the 'lcore_id'
being used for the first time.

Fixes: 9dc843eb273b ("power: extend guest channel API for reading")
Cc: stable@dpdk.org
Signed-off-by: Hongbo Zheng <zhenghongbo3@huawei.com>
Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
Reviewed-by: Reshma Pattan <reshma.pattan@intel.com>
Acked-by: David Hunt <david.hunt@intel.com>

diff --git a/lib/power/guest_channel.c b/lib/power/guest_channel.c
index 2f7507a..474dd92 100644 (file)
--- a/lib/power/guest_channel.c
+++ b/lib/power/guest_channel.c
@@ -166,6 +166,17 @@ int power_guest_channel_read_msg(void *pkt,
        if (pkt_len == 0 || pkt == NULL)
                return -1;
 
+       if (lcore_id >= RTE_MAX_LCORE) {
+               RTE_LOG(ERR, GUEST_CHANNEL, "Channel(%u) is out of range 0...%d\n",
+                               lcore_id, RTE_MAX_LCORE-1);
+               return -1;
+       }
+
+       if (global_fds[lcore_id] < 0) {
+               RTE_LOG(ERR, GUEST_CHANNEL, "Channel is not connected\n");
+               return -1;
+       }
+
        fds.fd = global_fds[lcore_id];
        fds.events = POLLIN;
 
@@ -179,17 +190,6 @@ int power_guest_channel_read_msg(void *pkt,
                return -1;
        }
 
-       if (lcore_id >= RTE_MAX_LCORE) {
-               RTE_LOG(ERR, GUEST_CHANNEL, "Channel(%u) is out of range 0...%d\n",
-                               lcore_id, RTE_MAX_LCORE-1);
-               return -1;
-       }
-
-       if (global_fds[lcore_id] < 0) {
-               RTE_LOG(ERR, GUEST_CHANNEL, "Channel is not connected\n");
-               return -1;
-       }
-
        while (pkt_len > 0) {
                ret = read(global_fds[lcore_id],
                                pkt, pkt_len);