[PATCH v10] vhost: fix use-after-free in fdset during shutdown

[Yehor Malikov <malikovyehor@gmail.com>]

From: Yehor Malikov <Yehor.Malikov@solidigm.com>

The fdset_event_dispatch thread runs in a loop checking the destroy
flag after each epoll_wait iteration. During process exit,
rte_eal_cleanup() frees hugepage memory while the fdset thread is
still running. Since the fdset structure was allocated with
rte_zmalloc() (hugepage-backed), accessing it after rte_eal_cleanup()
causes use-after-free.

Switch fdset allocation from rte_zmalloc/rte_free to libc
calloc/free. The fdset is a control-path structure that does not
need hugepage memory. Using libc allocation ensures the fdset
remains valid after rte_eal_cleanup() releases hugepages.

Fixes: e68a6feaa3b3 ("vhost: improve fdset initialization")

Signed-off-by: Yehor Malikov <Yehor.Malikov@solidigm.com>
---
 lib/vhost/fd_man.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/vhost/fd_man.c b/lib/vhost/fd_man.c
index f9147edee7..fae6d787b6 100644
--- a/lib/vhost/fd_man.c
+++ b/lib/vhost/fd_man.c
@@ -8,9 +8,10 @@
 #include <sys/epoll.h>
 #include <unistd.h>
 
+#include <stdlib.h>
+
 #include <rte_common.h>
 #include <rte_log.h>
-#include <rte_malloc.h>
 #include <rte_string_fns.h>
 #include <rte_thread.h>
 
@@ -94,7 +95,7 @@ fdset_init(const char *name)
 		return fdset;
 	}
 
-	fdset = rte_zmalloc(NULL, sizeof(*fdset), 0);
+	fdset = calloc(1, sizeof(*fdset));
 	if (!fdset) {
 		VHOST_FDMAN_LOG(ERR, "failed to alloc fdset %s", name);
 		goto err_unlock;
@@ -142,7 +143,7 @@ fdset_init(const char *name)
 err_epoll:
 	close(fdset->epfd);
 err_free:
-	rte_free(fdset);
+	free(fdset);
 err_unlock:
 	pthread_mutex_unlock(&fdsets_mutex);
 
-- 
2.52.0