From 218d11a8b071b23b76c484fd5f72a4fe3306801e Mon Sep 17 00:00:00 2001 From: Jonathan Corbet Date: Fri, 5 Dec 2008 16:12:48 -0700 Subject: Fix a race condition in FASYNC handling Changeset a238b790d5f99c7832f9b73ac8847025815b85f7 (Call fasync() functions without the BKL) introduced a race which could leave file->f_flags in a state inconsistent with what the underlying driver/filesystem believes. Revert that change, and also fix the same races in ioctl_fioasync() and ioctl_fionbio(). This is a minimal, short-term fix; the real fix will not involve the BKL. Reported-by: Oleg Nesterov Cc: Andi Kleen Cc: Al Viro Cc: stable@kernel.org Signed-off-by: Jonathan Corbet Signed-off-by: Linus Torvalds --- fs/ioctl.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'fs/ioctl.c') diff --git a/fs/ioctl.c b/fs/ioctl.c index d152856c371b..43e8b2c0664b 100644 --- a/fs/ioctl.c +++ b/fs/ioctl.c @@ -400,11 +400,9 @@ static int ioctl_fioasync(unsigned int fd, struct file *filp, /* Did FASYNC state change ? */ if ((flag ^ filp->f_flags) & FASYNC) { - if (filp->f_op && filp->f_op->fasync) { - lock_kernel(); + if (filp->f_op && filp->f_op->fasync) error = filp->f_op->fasync(fd, filp, on); - unlock_kernel(); - } else + else error = -ENOTTY; } if (error) @@ -440,11 +438,17 @@ int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd, break; case FIONBIO: + /* BKL needed to avoid races tweaking f_flags */ + lock_kernel(); error = ioctl_fionbio(filp, argp); + unlock_kernel(); break; case FIOASYNC: + /* BKL needed to avoid races tweaking f_flags */ + lock_kernel(); error = ioctl_fioasync(fd, filp, argp); + unlock_kernel(); break; case FIOQSIZE: -- cgit v1.2.2