From 8fed562e63f3bf7ab2ddabaf1b31de49e03c4083 Mon Sep 17 00:00:00 2001
From: David Gibson <david@gibson.dropbear.id.au>
Date: Wed, 2 Apr 2025 15:28:04 +1100
Subject: [PATCH] passt-repair: Correct off-by-one error verifying name
passt-repair will generate an error if the name it gets from the kernel is
too long or not NUL terminated. Downstream testing has reported
occasionally seeing this error in practice.
In turns out there is a trivial off-by-one error in the check: ev->len is
the length of the name, including terminating \0 characters, so to check
for a \0 at the end of the buffer we need to check ev->name[len - 1] not
ev->name[len].
Fixes: 42a854a52 ("pasta, passt-repair: Support multiple events per...")
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
passt-repair.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/passt-repair.c b/passt-repair.c
index 86f0293..440c77a 100644
--- a/passt-repair.c
+++ b/passt-repair.c
@@ -157,7 +157,7 @@ int main(int argc, char **argv)
}
} while (!found);
- if (ev->len > NAME_MAX + 1 || ev->name[ev->len] != '\0') {
+ if (ev->len > NAME_MAX + 1 || ev->name[ev->len - 1] != '\0') {
fprintf(stderr, "Invalid filename from inotify\n");
_exit(1);
}