From a84c51f26258270ff7c0a1176f948c52ccaca8f5 Mon Sep 17 00:00:00 2001 From: jilles Date: Sat, 9 Apr 2016 13:32:42 +0000 Subject: [PATCH] MFC r295385: semget(): Check for [EEXIST] error first. Although POSIX literally permits failing with [EINVAL] if IPC_CREAT and IPC_EXCL were both passed, the semaphore set already exists and has fewer semaphores than nsems, this does not allow an application to retry safely: if the [EINVAL] is actually because of the semmsl limit, an infinite loop would result. PR: 206927 git-svn-id: svn://svn.freebsd.org/base/stable/10@297747 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f --- sys/kern/sysv_sem.c | 10 +++++----- tools/regression/sysvsem/semtest.c | 9 +++++++++ 2 files changed, 14 insertions(+), 5 deletions(-) diff --git a/sys/kern/sysv_sem.c b/sys/kern/sysv_sem.c index 441cbfcd5..4337d4dbb 100644 --- a/sys/kern/sysv_sem.c +++ b/sys/kern/sysv_sem.c @@ -877,6 +877,11 @@ sys_semget(struct thread *td, struct semget_args *uap) } if (semid < seminfo.semmni) { DPRINTF(("found public key\n")); + if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { + DPRINTF(("not exclusive\n")); + error = EEXIST; + goto done2; + } if ((error = ipcperm(td, &sema[semid].u.sem_perm, semflg & 0700))) { goto done2; @@ -886,11 +891,6 @@ sys_semget(struct thread *td, struct semget_args *uap) error = EINVAL; goto done2; } - if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { - DPRINTF(("not exclusive\n")); - error = EEXIST; - goto done2; - } #ifdef MAC error = mac_sysvsem_check_semget(cred, &sema[semid]); if (error != 0) diff --git a/tools/regression/sysvsem/semtest.c b/tools/regression/sysvsem/semtest.c index 8a997d0bf..39c416403 100644 --- a/tools/regression/sysvsem/semtest.c +++ b/tools/regression/sysvsem/semtest.c @@ -152,6 +152,15 @@ main(int argc, char *argv[]) print_semid_ds(&s_ds, 0600); + errno = 0; + if (semget(semkey, 1, IPC_CREAT | IPC_EXCL | 0600) != -1 || + errno != EEXIST) + err(1, "semget IPC_EXCL 1 did not fail with [EEXIST]"); + errno = 0; + if (semget(semkey, 2, IPC_CREAT | IPC_EXCL | 0600) != -1 || + errno != EEXIST) + err(1, "semget IPC_EXCL 2 did not fail with [EEXIST]"); + for (child_count = 0; child_count < 5; child_count++) { switch ((child_pid = fork())) { case -1: -- 2.45.0