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Fri, 24 Jun 2022 19:36:52 GMT (envelope-from git) Date: Fri, 24 Jun 2022 19:36:52 GMT Message-Id: <202206241936.25OJaqFm084108@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Konstantin Belousov Subject: git: 78d5ef6505d7 - stable/13 - Fix a race between fork(2) and PROC_REAP_KILL subtree List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-all@freebsd.org X-BeenThere: dev-commits-src-all@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: kib X-Git-Repository: src X-Git-Refname: refs/heads/stable/13 X-Git-Reftype: branch X-Git-Commit: 78d5ef6505d71f3c123f9ca645dc4b8690a95471 Auto-Submitted: auto-generated ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; 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mx1.freebsd.org; none X-ThisMailContainsUnwantedMimeParts: N The branch stable/13 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=78d5ef6505d71f3c123f9ca645dc4b8690a95471 commit 78d5ef6505d71f3c123f9ca645dc4b8690a95471 Author: Konstantin Belousov AuthorDate: 2022-04-20 21:33:51 +0000 Commit: Konstantin Belousov CommitDate: 2022-06-24 14:45:45 +0000 Fix a race between fork(2) and PROC_REAP_KILL subtree (cherry picked from commit 39794d80ad900915e5c4940e9917ba5cb59a8634) --- sys/kern/kern_procctl.c | 34 ++++++++++++++++++++++++++++++---- 1 file changed, 30 insertions(+), 4 deletions(-) diff --git a/sys/kern/kern_procctl.c b/sys/kern/kern_procctl.c index 1a9f17de2d7a..83fcc57f8f78 100644 --- a/sys/kern/kern_procctl.c +++ b/sys/kern/kern_procctl.c @@ -31,6 +31,7 @@ __FBSDID("$FreeBSD$"); #include +#include #include #include #include @@ -293,14 +294,17 @@ reap_kill_children(struct thread *td, struct proc *reaper, } } -static void -reap_kill_subtree(struct thread *td, struct proc *p, struct proc *reaper, - struct procctl_reaper_kill *rk, ksiginfo_t *ksi, int *error) +static bool +reap_kill_subtree_once(struct thread *td, struct proc *p, struct proc *reaper, + struct procctl_reaper_kill *rk, ksiginfo_t *ksi, int *error, + struct unrhdr *pids) { struct reap_kill_tracker_head tracker; struct reap_kill_tracker *t; struct proc *p2; + bool res; + res = false; TAILQ_INIT(&tracker); reap_kill_sched(&tracker, reaper); while ((t = TAILQ_FIRST(&tracker)) != NULL) { @@ -313,10 +317,32 @@ reap_kill_subtree(struct thread *td, struct proc *p, struct proc *reaper, continue; if ((p2->p_treeflag & P_TREE_REAPER) != 0) reap_kill_sched(&tracker, p2); - reap_kill_proc(td, p2, ksi, rk, error); + if (alloc_unr_specific(pids, p2->p_pid) == p2->p_pid) { + reap_kill_proc(td, p2, ksi, rk, error); + res = true; + } } free(t, M_TEMP); } + return (res); +} + +static void +reap_kill_subtree(struct thread *td, struct proc *p, struct proc *reaper, + struct procctl_reaper_kill *rk, ksiginfo_t *ksi, int *error) +{ + struct unrhdr pids; + + /* + * pids records processes which were already signalled, to + * avoid doubling signals to them if iteration needs to be + * repeated. + */ + init_unrhdr(&pids, 1, PID_MAX, UNR_NO_MTX); + while (reap_kill_subtree_once(td, p, reaper, rk, ksi, error, &pids)) + ; + clean_unrhdr(&pids); + clear_unrhdr(&pids); } static bool