Date: Thu, 4 Feb 2021 23:15:57 GMT From: Jamie Gritton <jamie@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 7726fc9940d6 - stable/13 - MFC jail: fix dangling reference bug from 6754ae2572eb Message-ID: <202102042315.114NFvKS061529@gitrepo.freebsd.org>
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The branch stable/13 has been updated by jamie: URL: https://cgit.FreeBSD.org/src/commit/?id=7726fc9940d688af35753a374391de48bad1e1ca commit 7726fc9940d688af35753a374391de48bad1e1ca Author: Jamie Gritton <jamie@FreeBSD.org> AuthorDate: 2021-01-22 18:56:24 +0000 Commit: Jamie Gritton <jamie@FreeBSD.org> CommitDate: 2021-02-04 23:13:47 +0000 MFC jail: fix dangling reference bug from 6754ae2572eb The change to use refcounts for pr_uref was mishandled in prison_proc_free, so killing a jail's last process could add an extra reference, leaving it an unkillable zombie. (cherry picked from commit 195cd6ae2481dd5ad555ed65c226b6f20908d66a) --- sys/kern/kern_jail.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c index 318f81fb13be..064f1afa4133 100644 --- a/sys/kern/kern_jail.c +++ b/sys/kern/kern_jail.c @@ -2705,7 +2705,6 @@ prison_proc_hold(struct prison *pr) void prison_proc_free(struct prison *pr) { - int lasturef; /* * Locking is only required when releasing the last reference. @@ -2714,11 +2713,7 @@ prison_proc_free(struct prison *pr) */ KASSERT(refcount_load(&pr->pr_uref) > 0, ("Trying to kill a process in a dead prison (jid=%d)", pr->pr_id)); - if (refcount_release_if_not_last(&pr->pr_uref)) - return; - mtx_lock(&pr->pr_mtx); - lasturef = refcount_release(&pr->pr_uref); - if (lasturef) { + if (!refcount_release_if_not_last(&pr->pr_uref)) { /* * Don't remove the last user reference in this context, * which is expected to be a process that is not only locked, @@ -2726,11 +2721,8 @@ prison_proc_free(struct prison *pr) * prison_free() won't re-submit the task. */ refcount_acquire(&pr->pr_ref); - mtx_unlock(&pr->pr_mtx); taskqueue_enqueue(taskqueue_thread, &pr->pr_task); - return; } - mtx_unlock(&pr->pr_mtx); } /*
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