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| author | Jonathan Corbet <corbet@lwn.net> | 2008-12-05 16:12:48 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2008-12-13 15:29:14 -0800 |
| commit | 21b7c0e824f0e98242e625a15bea368ea72ebcbb (patch) | |
| tree | bb5883ca3e3fd82d9216f686c7a7aee9a9f1a191 /fs/fcntl.c | |
| parent | 5c7c64831c51516034a7099ba25718f7aaed19e4 (diff) | |
| download | lwn-21b7c0e824f0e98242e625a15bea368ea72ebcbb.tar.gz lwn-21b7c0e824f0e98242e625a15bea368ea72ebcbb.zip | |
Fix a race condition in FASYNC handling
commit 218d11a8b071b23b76c484fd5f72a4fe3306801e upstream.
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 <oleg@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs/fcntl.c')
| -rw-r--r-- | fs/fcntl.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/fcntl.c b/fs/fcntl.c index ac4f7db9f134..549daf8005fb 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -19,6 +19,7 @@ #include <linux/signal.h> #include <linux/rcupdate.h> #include <linux/pid_namespace.h> +#include <linux/smp_lock.h> #include <asm/poll.h> #include <asm/siginfo.h> @@ -175,6 +176,11 @@ static int setfl(int fd, struct file * filp, unsigned long arg) if (error) return error; + /* + * We still need a lock here for now to keep multiple FASYNC calls + * from racing with each other. + */ + lock_kernel(); if ((arg ^ filp->f_flags) & FASYNC) { if (filp->f_op && filp->f_op->fasync) { error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); @@ -185,6 +191,7 @@ static int setfl(int fd, struct file * filp, unsigned long arg) filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); out: + unlock_kernel(); return error; } |