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[84.3.50.134]) by smtp.gmail.com with ESMTPSA id b21sm3909109wmd.37.2020.01.18.09.11.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 18 Jan 2020 09:11:18 -0800 (PST) Date: Sat, 18 Jan 2020 18:11:16 +0100 From: Ingo Molnar To: Linus Torvalds Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Thomas Gleixner , Andrew Morton , Mathieu Desnoyers Subject: [GIT PULL] rseq fixes Message-ID: <20200118171116.GA7596@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus, Please pull the latest core-urgent-for-linus git tree from: git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core-urgent-for-linus # HEAD: 463f550fb47bede3a5d7d5177f363a6c3b45d50b rseq: Unregister rseq for clone CLONE_VM This tree contains two rseq bugfixes: - CLONE_VM !CLONE_THREAD didn't work properly, the kernel would end up corrupting the TLS of the parent. Technically a change in the ABI but the previous behavior couldn't resonably have been relied on by applications so this looks like a valid exception to the ABI rule. - Make the RSEQ_FLAG_UNREGISTER ABI behavior consistent with the handling of other flags. This is not thought to impact any applications either. ( Of course both are only one contrary regression report away from being reverted. ) Thanks, Ingo ------------------> Mathieu Desnoyers (2): rseq: Reject unknown flags on rseq unregister rseq: Unregister rseq for clone CLONE_VM include/linux/sched.h | 4 ++-- kernel/rseq.c | 2 ++ 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 467d26046416..716ad1d8d95e 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1929,11 +1929,11 @@ static inline void rseq_migrate(struct task_struct *t) /* * If parent process has a registered restartable sequences area, the - * child inherits. Only applies when forking a process, not a thread. + * child inherits. Unregister rseq for a clone with CLONE_VM set. */ static inline void rseq_fork(struct task_struct *t, unsigned long clone_flags) { - if (clone_flags & CLONE_THREAD) { + if (clone_flags & CLONE_VM) { t->rseq = NULL; t->rseq_sig = 0; t->rseq_event_mask = 0; diff --git a/kernel/rseq.c b/kernel/rseq.c index 27c48eb7de40..a4f86a9d6937 100644 --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -310,6 +310,8 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len, int ret; if (flags & RSEQ_FLAG_UNREGISTER) { + if (flags & ~RSEQ_FLAG_UNREGISTER) + return -EINVAL; /* Unregister rseq for current thread. */ if (current->rseq != rseq || !current->rseq) return -EINVAL;