eal: fix out of bound access when no CPU available

In the unlikely case when the dpdk application is started with no cpu
available in the [0, RTE_MAX_LCORE - 1] range, the master_lcore is
automatically chosen as RTE_MAX_LCORE which triggers an out of bound
access.

Either you have a crash then, or the initialisation fails later when
trying to pin the master thread on it.
In my test, with RTE_MAX_LCORE == 2:

$ taskset -c 2 ./master/app/testpmd --no-huge -m 512 --log-level *:debug
[...]
EAL: pthread_setaffinity_np failed
PANIC in eal_thread_init_master():
cannot set affinity
7: [./master/app/testpmd() [0x47f629]]

Bugzilla ID: 19
Fixes: 2eba8d21f3c9 ("eal: restrict cores auto detection")
Cc: stable@dpdk.org
Signed-off-by: David Marchand <david.marchand@redhat.com>

diff --git a/lib/librte_eal/common/eal_common_options.c b/lib/librte_eal/common/eal_common_options.c
index 4681333..80d7902 100644 (file)
--- a/lib/librte_eal/common/eal_common_options.c
+++ b/lib/librte_eal/common/eal_common_options.c
@@ -1388,6 +1388,8 @@ eal_adjust_config(struct internal_config *internal_cfg)
        /* default master lcore is the first one */
        if (!master_lcore_parsed) {
                cfg->master_lcore = rte_get_next_lcore(-1, 0, 0);
+               if (cfg->master_lcore >= RTE_MAX_LCORE)
+                       return -1;
                lcore_config[cfg->master_lcore].core_role = ROLE_RTE;
        }