autofs/autofs-5.1.7-refactor-lookup_prune_one_cache-a-bit.patch

76 lines
2.5 KiB
Diff

autofs-5.1.7 - refactor lookup_prune_one_cache() a bit
From: Ian Kent <raven@themaw.net>
Coverity: use: Using an unreliable value of "me" inside the second locked
section.
Change lookup_prune_one_cache() a little, move the location the next
key is set (before releasing the lock) and add a comment explaining
why we don't care about the side effects of the read lock release/
write lock aquire/write lock release/read lock reaquire.
Signed-off-by: Ian Kent <raven@themaw.net>
---
CHANGELOG | 1 +
daemon/lookup.c | 20 +++++++++++++++++++-
2 files changed, 20 insertions(+), 1 deletion(-)
diff --git a/CHANGELOG b/CHANGELOG
index 81461978..b79aebc8 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -63,6 +63,7 @@
- fix arg not used in error print.
- fix missing lock release in mount_subtree().
- fix double free in parse_mapent().
+- refactor lookup_prune_one_cache() a bit.
25/01/2021 autofs-5.1.7
- make bind mounts propagation slave by default.
diff --git a/daemon/lookup.c b/daemon/lookup.c
index 32dbc24d..3e9722e4 100644
--- a/daemon/lookup.c
+++ b/daemon/lookup.c
@@ -1375,7 +1375,6 @@ void lookup_prune_one_cache(struct autofs_point *ap, struct mapent_cache *mc, ti
}
key = strdup(me->key);
- me = cache_enumerate(mc, me);
/* Don't consider any entries with a wildcard */
if (!key || strchr(key, '*')) {
if (key)
@@ -1422,6 +1421,7 @@ void lookup_prune_one_cache(struct autofs_point *ap, struct mapent_cache *mc, ti
if (valid)
cache_unlock(valid->mc);
+ me = cache_enumerate(mc, me);
if (me)
next_key = strdup(me->key);
@@ -1456,6 +1456,24 @@ void lookup_prune_one_cache(struct autofs_point *ap, struct mapent_cache *mc, ti
next:
cache_readlock(mc);
if (next_key) {
+ /* The lock release and reaquire above can mean
+ * a number of things could happen.
+ *
+ * First, mapents could be added between the
+ * current mapent and the mapent of next_key.
+ * Don't care about that because there's no
+ * need to prune newly added entries.
+ *
+ * Second, the next mapent data could have
+ * changed. Don't care about that either since
+ * we are looking to prune stale map entries
+ * and don't care when they become stale.
+ *
+ * Finally, the mapent of next_key could have
+ * gone away. Again don't care about this either,
+ * the loop will exit prematurely so just wait
+ * until the next prune and try again.
+ */
me = cache_lookup_distinct(mc, next_key);
free(next_key);
}