[PATCH] eal/linux: unregister alarm callback before free ptr

[Rui Ferreira]

This was flagged by Address sanitizer as a use after free. The
intr_handle ptr is shared between the main thread and the interrupt
thread, and the interrupt thread can dereference the ptr after free
is called when the main thread cleans up (from the alarm callback).

The interrupt thread never terminates (eal_intr_thread_main) so
use rte_intr_callback_unregister_sync during cleanup to
ensure the callback is removed before freeing the ptr.

To be more defensive clear out the pointer and registration
variable if we can unregister.

Bugzilla ID: 1683

Signed-off-by: Rui Ferreira <rui.ferreira1 at h-partners.com>
---
 .mailmap                  | 1 +
 lib/eal/linux/eal_alarm.c | 9 ++++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/.mailmap b/.mailmap
index d8439b79ce..907c5ea967 100644
--- a/.mailmap
+++ b/.mailmap
@@ -1332,6 +1332,7 @@ Rosen Xu <rosen.xu at altera.com> <rosen.xu at intel.com>
 Roy Franz <roy.franz at cavium.com>
 Roy Pledge <roy.pledge at nxp.com>
 Roy Shterman <roy.shterman at vastdata.com>
+Rui Ferreira <rui.ferreira1 at h-partners.com>
 Ruifeng Wang <ruifeng.wang at arm.com>
 Rushil Gupta <rushilg at google.com>
 Ryan E Hall <ryan.e.hall at intel.com>
diff --git a/lib/eal/linux/eal_alarm.c b/lib/eal/linux/eal_alarm.c
index b216a007a3..eb6a21d4f0 100644
--- a/lib/eal/linux/eal_alarm.c
+++ b/lib/eal/linux/eal_alarm.c
@@ -57,7 +57,14 @@ static void eal_alarm_callback(void *arg);
 void
 rte_eal_alarm_cleanup(void)
 {
-	rte_intr_instance_free(intr_handle);
+	/* unregister callback using intr_handle in interrupt thread */
+	int ret = rte_intr_callback_unregister_sync(intr_handle,
+						eal_alarm_callback, (void *)-1);
+	if (ret >= 0) {
+		rte_intr_instance_free(intr_handle);
+		intr_handle = NULL;
+		handler_registered = 0;
+	}
 }
 
 int
-- 
2.35.3