136 lines
3.9 KiB
Diff
136 lines
3.9 KiB
Diff
autofs-5.1.7 - fix inconsistent locking in umount_subtree_mounts()
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From: Ian Kent <raven@themaw.net>
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Some map entry cache locking inconsistencies have crept in.
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In umount_subtree_mounts() the cache write lock should be held when
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deleting multi-mount cache entries.
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Signed-off-by: Ian Kent <raven@themaw.net>
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---
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CHANGELOG | 1 +
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daemon/automount.c | 42 ++++++++++++++++++++++++++++++------------
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lib/mounts.c | 8 --------
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3 files changed, 31 insertions(+), 20 deletions(-)
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diff --git a/CHANGELOG b/CHANGELOG
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index 1dded118..64e619ec 100644
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--- a/CHANGELOG
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+++ b/CHANGELOG
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@@ -15,6 +15,7 @@
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- eliminate clean_stale_multi_triggers().
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- simplify mount_subtree() mount check.
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- fix mnts_get_expire_list() expire list construction.
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+- fix inconsistent locking in umount_subtree_mounts().
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25/01/2021 autofs-5.1.7
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- make bind mounts propagation slave by default.
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diff --git a/daemon/automount.c b/daemon/automount.c
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index 7fa92877..93bd8556 100644
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--- a/daemon/automount.c
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+++ b/daemon/automount.c
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@@ -527,8 +527,11 @@ static int umount_subtree_mounts(struct autofs_point *ap, const char *path, unsi
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struct mapent_cache *mc;
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struct mapent *me;
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unsigned int is_mm_root = 0;
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+ int cur_state;
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int left;
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+ pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cur_state);
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+
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me = lookup_source_mapent(ap, path, LKP_DISTINCT);
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if (!me) {
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char *ind_key;
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@@ -548,11 +551,11 @@ static int umount_subtree_mounts(struct autofs_point *ap, const char *path, unsi
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left = 0;
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if (me && me->multi) {
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- char root[PATH_MAX];
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+ char root[PATH_MAX + 1];
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+ char key[PATH_MAX + 1];
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+ struct mapent *tmp;
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+ int status;
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char *base;
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- int cur_state;
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-
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- pthread_cleanup_push(cache_lock_cleanup, mc);
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if (!strchr(me->multi->key, '/'))
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/* Indirect multi-mount root */
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@@ -567,25 +570,40 @@ static int umount_subtree_mounts(struct autofs_point *ap, const char *path, unsi
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else
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base = me->key + strlen(root);
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- pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cur_state);
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- /* Lock the closest parent nesting point for umount */
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- cache_multi_writelock(me->parent);
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- if (umount_multi_triggers(ap, me, root, base)) {
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+ left = umount_multi_triggers(ap, me, root, base);
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+ if (left) {
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warn(ap->logopt,
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"some offset mounts still present under %s", path);
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+ }
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+
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+ strcpy(key, me->key);
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+
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+ cache_unlock(mc);
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+ cache_writelock(mc);
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+ tmp = cache_lookup_distinct(mc, key);
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+ /* mapent went away while we waited? */
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+ if (tmp != me) {
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+ cache_unlock(mc);
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+ pthread_setcancelstate(cur_state, NULL);
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+ return 0;
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+ }
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+
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+ if (!left && is_mm_root) {
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+ status = cache_delete_offset_list(mc, me->key);
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+ if (status != CHE_OK)
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+ warn(ap->logopt, "couldn't delete offset list");
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left++;
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}
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- cache_multi_unlock(me->parent);
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+
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if (ap->entry->maps &&
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(ap->entry->maps->flags & MAP_FLAG_FORMAT_AMD))
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cache_pop_mapent(me);
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- pthread_setcancelstate(cur_state, NULL);
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- pthread_cleanup_pop(0);
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}
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-
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if (me)
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cache_unlock(mc);
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+ pthread_setcancelstate(cur_state, NULL);
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+
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if (left || is_autofs_fs)
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return left;
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diff --git a/lib/mounts.c b/lib/mounts.c
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index 87813b16..5ebfe5fd 100644
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--- a/lib/mounts.c
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+++ b/lib/mounts.c
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@@ -2736,9 +2736,6 @@ int umount_multi_triggers(struct autofs_point *ap, struct mapent *me, char *root
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left = do_umount_multi_triggers(ap, me, root, base);
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if (!left && me->multi == me) {
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- struct mapent_cache *mc = me->mc;
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- int status;
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-
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/*
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* Special case.
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* If we can't umount the root container then we can't
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@@ -2756,11 +2753,6 @@ int umount_multi_triggers(struct autofs_point *ap, struct mapent *me, char *root
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}
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}
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- /* We're done - clean out the offsets */
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- status = cache_delete_offset_list(mc, me->key);
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- if (status != CHE_OK)
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- warn(ap->logopt, "couldn't delete offset list");
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-
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/* check for mounted mount entry and remove it if found */
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mnts_remove_mount(root, MNTS_MOUNTED);
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}
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