From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- fs/signalfd.c | 351 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 351 insertions(+) create mode 100644 fs/signalfd.c (limited to 'fs/signalfd.c') diff --git a/fs/signalfd.c b/fs/signalfd.c new file mode 100644 index 000000000..dff53745e --- /dev/null +++ b/fs/signalfd.c @@ -0,0 +1,351 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/signalfd.c + * + * Copyright (C) 2003 Linus Torvalds + * + * Mon Mar 5, 2007: Davide Libenzi + * Changed ->read() to return a siginfo strcture instead of signal number. + * Fixed locking in ->poll(). + * Added sighand-detach notification. + * Added fd re-use in sys_signalfd() syscall. + * Now using anonymous inode source. + * Thanks to Oleg Nesterov for useful code review and suggestions. + * More comments and suggestions from Arnd Bergmann. + * Sat May 19, 2007: Davi E. M. Arnaut + * Retrieve multiple signals with one read() call + * Sun Jul 15, 2007: Davide Libenzi + * Attach to the sighand only during read() and poll(). + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +void signalfd_cleanup(struct sighand_struct *sighand) +{ + wake_up_pollfree(&sighand->signalfd_wqh); +} + +struct signalfd_ctx { + sigset_t sigmask; +}; + +static int signalfd_release(struct inode *inode, struct file *file) +{ + kfree(file->private_data); + return 0; +} + +static __poll_t signalfd_poll(struct file *file, poll_table *wait) +{ + struct signalfd_ctx *ctx = file->private_data; + __poll_t events = 0; + + poll_wait(file, ¤t->sighand->signalfd_wqh, wait); + + spin_lock_irq(¤t->sighand->siglock); + if (next_signal(¤t->pending, &ctx->sigmask) || + next_signal(¤t->signal->shared_pending, + &ctx->sigmask)) + events |= EPOLLIN; + spin_unlock_irq(¤t->sighand->siglock); + + return events; +} + +/* + * Copied from copy_siginfo_to_user() in kernel/signal.c + */ +static int signalfd_copyinfo(struct iov_iter *to, kernel_siginfo_t const *kinfo) +{ + struct signalfd_siginfo new; + + BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128); + + /* + * Unused members should be zero ... + */ + memset(&new, 0, sizeof(new)); + + /* + * If you change siginfo_t structure, please be sure + * this code is fixed accordingly. + */ + new.ssi_signo = kinfo->si_signo; + new.ssi_errno = kinfo->si_errno; + new.ssi_code = kinfo->si_code; + switch (siginfo_layout(kinfo->si_signo, kinfo->si_code)) { + case SIL_KILL: + new.ssi_pid = kinfo->si_pid; + new.ssi_uid = kinfo->si_uid; + break; + case SIL_TIMER: + new.ssi_tid = kinfo->si_tid; + new.ssi_overrun = kinfo->si_overrun; + new.ssi_ptr = (long) kinfo->si_ptr; + new.ssi_int = kinfo->si_int; + break; + case SIL_POLL: + new.ssi_band = kinfo->si_band; + new.ssi_fd = kinfo->si_fd; + break; + case SIL_FAULT_BNDERR: + case SIL_FAULT_PKUERR: + case SIL_FAULT_PERF_EVENT: + /* + * Fall through to the SIL_FAULT case. SIL_FAULT_BNDERR, + * SIL_FAULT_PKUERR, and SIL_FAULT_PERF_EVENT are only + * generated by faults that deliver them synchronously to + * userspace. In case someone injects one of these signals + * and signalfd catches it treat it as SIL_FAULT. + */ + case SIL_FAULT: + new.ssi_addr = (long) kinfo->si_addr; + break; + case SIL_FAULT_TRAPNO: + new.ssi_addr = (long) kinfo->si_addr; + new.ssi_trapno = kinfo->si_trapno; + break; + case SIL_FAULT_MCEERR: + new.ssi_addr = (long) kinfo->si_addr; + new.ssi_addr_lsb = (short) kinfo->si_addr_lsb; + break; + case SIL_CHLD: + new.ssi_pid = kinfo->si_pid; + new.ssi_uid = kinfo->si_uid; + new.ssi_status = kinfo->si_status; + new.ssi_utime = kinfo->si_utime; + new.ssi_stime = kinfo->si_stime; + break; + case SIL_RT: + /* + * This case catches also the signals queued by sigqueue(). + */ + new.ssi_pid = kinfo->si_pid; + new.ssi_uid = kinfo->si_uid; + new.ssi_ptr = (long) kinfo->si_ptr; + new.ssi_int = kinfo->si_int; + break; + case SIL_SYS: + new.ssi_call_addr = (long) kinfo->si_call_addr; + new.ssi_syscall = kinfo->si_syscall; + new.ssi_arch = kinfo->si_arch; + break; + } + + if (!copy_to_iter_full(&new, sizeof(struct signalfd_siginfo), to)) + return -EFAULT; + + return sizeof(struct signalfd_siginfo); +} + +static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, kernel_siginfo_t *info, + int nonblock) +{ + enum pid_type type; + ssize_t ret; + DECLARE_WAITQUEUE(wait, current); + + spin_lock_irq(¤t->sighand->siglock); + ret = dequeue_signal(&ctx->sigmask, info, &type); + switch (ret) { + case 0: + if (!nonblock) + break; + ret = -EAGAIN; + fallthrough; + default: + spin_unlock_irq(¤t->sighand->siglock); + return ret; + } + + add_wait_queue(¤t->sighand->signalfd_wqh, &wait); + for (;;) { + set_current_state(TASK_INTERRUPTIBLE); + ret = dequeue_signal(&ctx->sigmask, info, &type); + if (ret != 0) + break; + if (signal_pending(current)) { + ret = -ERESTARTSYS; + break; + } + spin_unlock_irq(¤t->sighand->siglock); + schedule(); + spin_lock_irq(¤t->sighand->siglock); + } + spin_unlock_irq(¤t->sighand->siglock); + + remove_wait_queue(¤t->sighand->signalfd_wqh, &wait); + __set_current_state(TASK_RUNNING); + + return ret; +} + +/* + * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative + * error code. The "count" parameter must be at least the size of a + * "struct signalfd_siginfo". + */ +static ssize_t signalfd_read_iter(struct kiocb *iocb, struct iov_iter *to) +{ + struct file *file = iocb->ki_filp; + struct signalfd_ctx *ctx = file->private_data; + size_t count = iov_iter_count(to); + ssize_t ret, total = 0; + kernel_siginfo_t info; + bool nonblock; + + count /= sizeof(struct signalfd_siginfo); + if (!count) + return -EINVAL; + + nonblock = file->f_flags & O_NONBLOCK || iocb->ki_flags & IOCB_NOWAIT; + do { + ret = signalfd_dequeue(ctx, &info, nonblock); + if (unlikely(ret <= 0)) + break; + ret = signalfd_copyinfo(to, &info); + if (ret < 0) + break; + total += ret; + nonblock = 1; + } while (--count); + + return total ? total: ret; +} + +#ifdef CONFIG_PROC_FS +static void signalfd_show_fdinfo(struct seq_file *m, struct file *f) +{ + struct signalfd_ctx *ctx = f->private_data; + sigset_t sigmask; + + sigmask = ctx->sigmask; + signotset(&sigmask); + render_sigset_t(m, "sigmask:\t", &sigmask); +} +#endif + +static const struct file_operations signalfd_fops = { +#ifdef CONFIG_PROC_FS + .show_fdinfo = signalfd_show_fdinfo, +#endif + .release = signalfd_release, + .poll = signalfd_poll, + .read_iter = signalfd_read_iter, + .llseek = noop_llseek, +}; + +static int do_signalfd4(int ufd, sigset_t *mask, int flags) +{ + /* Check the SFD_* constants for consistency. */ + BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC); + BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK); + + if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK)) + return -EINVAL; + + sigdelsetmask(mask, sigmask(SIGKILL) | sigmask(SIGSTOP)); + signotset(mask); + + if (ufd == -1) { + int fd; + struct signalfd_ctx *ctx __free(kfree) = NULL; + + ctx = kmalloc_obj(*ctx); + if (!ctx) + return -ENOMEM; + + ctx->sigmask = *mask; + + fd = FD_ADD(flags & O_CLOEXEC, + anon_inode_getfile_fmode( + "[signalfd]", &signalfd_fops, ctx, + O_RDWR | (flags & O_NONBLOCK), FMODE_NOWAIT)); + if (fd >= 0) + retain_and_null_ptr(ctx); + return fd; + } else { + struct signalfd_ctx *ctx; + + CLASS(fd, f)(ufd); + if (fd_empty(f)) + return -EBADF; + ctx = fd_file(f)->private_data; + if (fd_file(f)->f_op != &signalfd_fops) + return -EINVAL; + spin_lock_irq(¤t->sighand->siglock); + ctx->sigmask = *mask; + spin_unlock_irq(¤t->sighand->siglock); + + wake_up(¤t->sighand->signalfd_wqh); + } + + return ufd; +} + +SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask, + size_t, sizemask, int, flags) +{ + sigset_t mask; + + if (sizemask != sizeof(sigset_t)) + return -EINVAL; + if (copy_from_user(&mask, user_mask, sizeof(mask))) + return -EFAULT; + return do_signalfd4(ufd, &mask, flags); +} + +SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask, + size_t, sizemask) +{ + sigset_t mask; + + if (sizemask != sizeof(sigset_t)) + return -EINVAL; + if (copy_from_user(&mask, user_mask, sizeof(mask))) + return -EFAULT; + return do_signalfd4(ufd, &mask, 0); +} + +#ifdef CONFIG_COMPAT +static long do_compat_signalfd4(int ufd, + const compat_sigset_t __user *user_mask, + compat_size_t sigsetsize, int flags) +{ + sigset_t mask; + + if (sigsetsize != sizeof(compat_sigset_t)) + return -EINVAL; + if (get_compat_sigset(&mask, user_mask)) + return -EFAULT; + return do_signalfd4(ufd, &mask, flags); +} + +COMPAT_SYSCALL_DEFINE4(signalfd4, int, ufd, + const compat_sigset_t __user *, user_mask, + compat_size_t, sigsetsize, + int, flags) +{ + return do_compat_signalfd4(ufd, user_mask, sigsetsize, flags); +} + +COMPAT_SYSCALL_DEFINE3(signalfd, int, ufd, + const compat_sigset_t __user *, user_mask, + compat_size_t, sigsetsize) +{ + return do_compat_signalfd4(ufd, user_mask, sigsetsize, 0); +} +#endif -- cgit v1.3.1