From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AE2A21A9B46; Thu, 28 May 2026 20:52:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780001549; cv=none; b=flHyOqCQBkShEXV4fg/1cfKiU5slpPuRX/EjJ6zzIbNCB4hZAAFKmBkS7iT39K9FTQTFZBxIPVAiR2Q6HvqwkQqmmShWaiREUhOslKVuQ9RPiXGID89wYiJIwt7uksGMFZ5a8haMgZccvwaQN4V6eXR3qy6tGFhW7/aYwR2yN54= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780001549; c=relaxed/simple; bh=Chot+yQ91bWcrHWRdO7NKYZp3/QXTDmd575pKkkSVm4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Fx1HKRiCPdQCQ6wQpVyIVHrnII4ZfuT0kGJWWx9AP3Sf3jq0bnB32n0KyvcDcpOz+qzNhmzO2u3vENNd5j2afef24iKd6gdKpyXDOFphHxcq2aX38Zw68Qhz1CndIIx6p9k/1MDof/EsNdt+JjOrsWnx4mGIuUM6H7UdcannhpU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=PZfMjsB9; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="PZfMjsB9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 169E61F000E9; Thu, 28 May 2026 20:52:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780001548; bh=D9RQiyiXVdhGpF0gzSyAOT04aSujfOreFnX6Y90a0PI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=PZfMjsB9VpZaaBdSM0wHvFJSuIceC+l07js9NrqEWlETJH+euct42e5cYBgsEuk6s f5yc3mRxQCw1myyudRNhoDnPEh6WlnXRkZ8gN8Y8o6LPQJ+bVXdkC0IEpKKnh0buJ1 2YvhAPacxmLJ/X0h9wS2zFHDbk7Mmhe1VxWVpcGs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Peter Zijlstra (Intel)" , Oleg Nesterov , Sasha Levin Subject: [PATCH 6.6 167/186] ptrace: Convert ptrace_attach() to use lock guards Date: Thu, 28 May 2026 21:50:47 +0200 Message-ID: <20260528194933.473272852@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260528194928.941004471@linuxfoundation.org> References: <20260528194928.941004471@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Zijlstra [ Upstream commit 5431fdd2c181dd2eac218e45b44deb2925fa48f0 ] Created as testing for the conditional guard infrastructure. Specifically this makes use of the following form: scoped_cond_guard (mutex_intr, return -ERESTARTNOINTR, &task->signal->cred_guard_mutex) { ... } ... return 0; Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Oleg Nesterov Link: https://lkml.kernel.org/r/20231102110706.568467727%40infradead.org Stable-dep-of: 60a1969fae62 ("ALSA: seq: Serialize UMP output teardown with event_input") Signed-off-by: Sasha Levin --- include/linux/sched/task.h | 2 + include/linux/spinlock.h | 26 ++++++++ kernel/ptrace.c | 128 ++++++++++++++++++------------------- 3 files changed, 89 insertions(+), 67 deletions(-) diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index 8dbecab4c4000..fc19837c8083e 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -227,4 +227,6 @@ static inline void task_unlock(struct task_struct *p) spin_unlock(&p->alloc_lock); } +DEFINE_GUARD(task_lock, struct task_struct *, task_lock(_T), task_unlock(_T)) + #endif /* _LINUX_SCHED_TASK_H */ diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index ceb56b39c70f7..90bc853cafb6a 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -548,5 +548,31 @@ DEFINE_LOCK_GUARD_1(spinlock_irqsave, spinlock_t, DEFINE_LOCK_GUARD_1_COND(spinlock_irqsave, _try, spin_trylock_irqsave(_T->lock, _T->flags)) +DEFINE_LOCK_GUARD_1(read_lock, rwlock_t, + read_lock(_T->lock), + read_unlock(_T->lock)) + +DEFINE_LOCK_GUARD_1(read_lock_irq, rwlock_t, + read_lock_irq(_T->lock), + read_unlock_irq(_T->lock)) + +DEFINE_LOCK_GUARD_1(read_lock_irqsave, rwlock_t, + read_lock_irqsave(_T->lock, _T->flags), + read_unlock_irqrestore(_T->lock, _T->flags), + unsigned long flags) + +DEFINE_LOCK_GUARD_1(write_lock, rwlock_t, + write_lock(_T->lock), + write_unlock(_T->lock)) + +DEFINE_LOCK_GUARD_1(write_lock_irq, rwlock_t, + write_lock_irq(_T->lock), + write_unlock_irq(_T->lock)) + +DEFINE_LOCK_GUARD_1(write_lock_irqsave, rwlock_t, + write_lock_irqsave(_T->lock, _T->flags), + write_unlock_irqrestore(_T->lock, _T->flags), + unsigned long flags) + #undef __LINUX_INSIDE_SPINLOCK_H #endif /* __LINUX_SPINLOCK_H */ diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 3c7d122a37fb4..6196a495d9c0c 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -396,6 +396,34 @@ static int check_ptrace_options(unsigned long data) return 0; } +static inline void ptrace_set_stopped(struct task_struct *task) +{ + guard(spinlock)(&task->sighand->siglock); + + /* + * If the task is already STOPPED, set JOBCTL_TRAP_STOP and + * TRAPPING, and kick it so that it transits to TRACED. TRAPPING + * will be cleared if the child completes the transition or any + * event which clears the group stop states happens. We'll wait + * for the transition to complete before returning from this + * function. + * + * This hides STOPPED -> RUNNING -> TRACED transition from the + * attaching thread but a different thread in the same group can + * still observe the transient RUNNING state. IOW, if another + * thread's WNOHANG wait(2) on the stopped tracee races against + * ATTACH, the wait(2) may fail due to the transient RUNNING. + * + * The following task_is_stopped() test is safe as both transitions + * in and out of STOPPED are protected by siglock. + */ + if (task_is_stopped(task) && + task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING)) { + task->jobctl &= ~JOBCTL_STOPPED; + signal_wake_up_state(task, __TASK_STOPPED); + } +} + static int ptrace_attach(struct task_struct *task, long request, unsigned long addr, unsigned long flags) @@ -403,17 +431,17 @@ static int ptrace_attach(struct task_struct *task, long request, bool seize = (request == PTRACE_SEIZE); int retval; - retval = -EIO; if (seize) { if (addr != 0) - goto out; + return -EIO; /* * This duplicates the check in check_ptrace_options() because * ptrace_attach() and ptrace_setoptions() have historically * used different error codes for unknown ptrace options. */ if (flags & ~(unsigned long)PTRACE_O_MASK) - goto out; + return -EIO; + retval = check_ptrace_options(flags); if (retval) return retval; @@ -424,88 +452,54 @@ static int ptrace_attach(struct task_struct *task, long request, audit_ptrace(task); - retval = -EPERM; if (unlikely(task->flags & PF_KTHREAD)) - goto out; + return -EPERM; if (same_thread_group(task, current)) - goto out; + return -EPERM; /* * Protect exec's credential calculations against our interference; * SUID, SGID and LSM creds get determined differently * under ptrace. */ - retval = -ERESTARTNOINTR; - if (mutex_lock_interruptible(&task->signal->cred_guard_mutex)) - goto out; + scoped_cond_guard (mutex_intr, return -ERESTARTNOINTR, + &task->signal->cred_guard_mutex) { - task_lock(task); - retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS); - task_unlock(task); - if (retval) - goto unlock_creds; + scoped_guard (task_lock, task) { + retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS); + if (retval) + return retval; + } - write_lock_irq(&tasklist_lock); - retval = -EPERM; - if (unlikely(task->exit_state)) - goto unlock_tasklist; - if (task->ptrace) - goto unlock_tasklist; + scoped_guard (write_lock_irq, &tasklist_lock) { + if (unlikely(task->exit_state)) + return -EPERM; + if (task->ptrace) + return -EPERM; - task->ptrace = flags; + task->ptrace = flags; - ptrace_link(task, current); + ptrace_link(task, current); - /* SEIZE doesn't trap tracee on attach */ - if (!seize) - send_sig_info(SIGSTOP, SEND_SIG_PRIV, task); + /* SEIZE doesn't trap tracee on attach */ + if (!seize) + send_sig_info(SIGSTOP, SEND_SIG_PRIV, task); - spin_lock(&task->sighand->siglock); + ptrace_set_stopped(task); + } + } /* - * If the task is already STOPPED, set JOBCTL_TRAP_STOP and - * TRAPPING, and kick it so that it transits to TRACED. TRAPPING - * will be cleared if the child completes the transition or any - * event which clears the group stop states happens. We'll wait - * for the transition to complete before returning from this - * function. - * - * This hides STOPPED -> RUNNING -> TRACED transition from the - * attaching thread but a different thread in the same group can - * still observe the transient RUNNING state. IOW, if another - * thread's WNOHANG wait(2) on the stopped tracee races against - * ATTACH, the wait(2) may fail due to the transient RUNNING. - * - * The following task_is_stopped() test is safe as both transitions - * in and out of STOPPED are protected by siglock. + * We do not bother to change retval or clear JOBCTL_TRAPPING + * if wait_on_bit() was interrupted by SIGKILL. The tracer will + * not return to user-mode, it will exit and clear this bit in + * __ptrace_unlink() if it wasn't already cleared by the tracee; + * and until then nobody can ptrace this task. */ - if (task_is_stopped(task) && - task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING)) { - task->jobctl &= ~JOBCTL_STOPPED; - signal_wake_up_state(task, __TASK_STOPPED); - } - - spin_unlock(&task->sighand->siglock); - - retval = 0; -unlock_tasklist: - write_unlock_irq(&tasklist_lock); -unlock_creds: - mutex_unlock(&task->signal->cred_guard_mutex); -out: - if (!retval) { - /* - * We do not bother to change retval or clear JOBCTL_TRAPPING - * if wait_on_bit() was interrupted by SIGKILL. The tracer will - * not return to user-mode, it will exit and clear this bit in - * __ptrace_unlink() if it wasn't already cleared by the tracee; - * and until then nobody can ptrace this task. - */ - wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT, TASK_KILLABLE); - proc_ptrace_connector(task, PTRACE_ATTACH); - } + wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT, TASK_KILLABLE); + proc_ptrace_connector(task, PTRACE_ATTACH); - return retval; + return 0; } /** -- 2.53.0