[PATCH v2 2/2] pasta: Terminate inotify buffer, skip nameless events in netns watch

[Aditya Merchant <adityamerchant08@gmail.com>]

In pasta_netns_quit_inotify_handler(), we compare the name of each event
we read with the base name of the namespace, but we don't make sure that
the buffer we read events into is zero-terminated. Events without a name,
such as the IN_IGNORED we get once the watch is removed, also have no
name to compare: for those, ev->name points past the end of the event.

Terminate the buffer, as wait_for_socket() in passt-repair does, and
skip events without a name.

Suggested-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Aditya Merchant <adityamerchant08@gmail.com>
---
 pasta.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/pasta.c b/pasta.c
index 4cd58fd..5ef678d 100644
--- a/pasta.c
+++ b/pasta.c
@@ -537,10 +537,13 @@ void pasta_netns_quit_inotify_handler(const struct ctx *c, int inotify_fd)
 	if ((n = read(inotify_fd, buf, sizeof(buf))) < (ssize_t)sizeof(*ev))
 		return;
 
+	/* cppcheck-suppress [negativeIndex, unmatchedSuppression] */
+	buf[n - 1] = '\0';
 	for (p = buf; p < buf + n; p += sizeof(*ev) + ev->len) {
 		ev = (const struct inotify_event *)p;
 
-		if (!strncmp(ev->name, c->netns_base, sizeof(c->netns_base))) {
+		if (ev->len &&
+		    !strncmp(ev->name, c->netns_base, sizeof(c->netns_base))) {
 			info("Namespace %s is gone, exiting", c->netns_base);
 			passt_exit(EXIT_SUCCESS);
 		}
-- 
2.50.1 (Apple Git-155)