[dpdk-dev] [PATCH v2] lib/librte_power: fix using variables before validity check

[Min Hu (Connor)]

From: HongBo Zheng <zhenghong...@huawei.com>

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: sta...@dpdk.org

Signed-off-by: HongBo Zheng <zhenghong...@huawei.com>
Signed-off-by: Min Hu (Connor) <humi...@huawei.com>
---
v2:
* "global_fds[lcore_id]"  check may move before the line
"fds.fd = global_fds[lcore_id].
---
 lib/power/guest_channel.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/lib/power/guest_channel.c b/lib/power/guest_channel.c
index 2f7507a..474dd92 100644
--- 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);
-- 
2.7.4