From 89cc8eef9ba6440a5f1772bb2cd200da9b4890d9 Mon Sep 17 00:00:00 2001 From: Yong He Date: Wed, 10 Apr 2019 14:16:36 -0700 Subject: DATA RACE in fs.(*Dirent).fullName add renameMu.Lock when oldParent == newParent in order to avoid data race in following report: WARNING: DATA RACE Read at 0x00c000ba2160 by goroutine 405: gvisor.googlesource.com/gvisor/pkg/sentry/fs.(*Dirent).fullName() pkg/sentry/fs/dirent.go:246 +0x6c gvisor.googlesource.com/gvisor/pkg/sentry/fs.(*Dirent).FullName() pkg/sentry/fs/dirent.go:356 +0x8b gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*FDMap).String() pkg/sentry/kernel/fd_map.go:135 +0x1e0 fmt.(*pp).handleMethods() GOROOT/src/fmt/print.go:603 +0x404 fmt.(*pp).printArg() GOROOT/src/fmt/print.go:686 +0x255 fmt.(*pp).doPrintf() GOROOT/src/fmt/print.go:1003 +0x33f fmt.Fprintf() GOROOT/src/fmt/print.go:188 +0x7f gvisor.googlesource.com/gvisor/pkg/log.(*Writer).Emit() pkg/log/log.go:121 +0x89 gvisor.googlesource.com/gvisor/pkg/log.GoogleEmitter.Emit() pkg/log/glog.go:162 +0x1acc gvisor.googlesource.com/gvisor/pkg/log.(*GoogleEmitter).Emit() :1 +0xe1 gvisor.googlesource.com/gvisor/pkg/log.(*BasicLogger).Debugf() pkg/log/log.go:177 +0x111 gvisor.googlesource.com/gvisor/pkg/log.Debugf() pkg/log/log.go:235 +0x66 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).Debugf() pkg/sentry/kernel/task_log.go:48 +0xfe gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).DebugDumpState() pkg/sentry/kernel/task_log.go:66 +0x11f gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*runApp).execute() pkg/sentry/kernel/task_run.go:272 +0xc80 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).run() pkg/sentry/kernel/task_run.go:91 +0x24b Previous write at 0x00c000ba2160 by goroutine 423: gvisor.googlesource.com/gvisor/pkg/sentry/fs.Rename() pkg/sentry/fs/dirent.go:1628 +0x61f gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.renameAt.func1.1() pkg/sentry/syscalls/linux/sys_file.go:1864 +0x1f8 gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.fileOpAt( gvisor.googlesource.com/g/linux/sys_file.go:51 +0x20f gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.renameAt.func1() pkg/sentry/syscalls/linux/sys_file.go:1852 +0x218 gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.fileOpAt() pkg/sentry/syscalls/linux/sys_file.go:51 +0x20f gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.renameAt() pkg/sentry/syscalls/linux/sys_file.go:1840 +0x180 gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.Rename() pkg/sentry/syscalls/linux/sys_file.go:1873 +0x60 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).executeSyscall() pkg/sentry/kernel/task_syscall.go:165 +0x17a gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke() pkg/sentry/kernel/task_syscall.go:283 +0xb4 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter() pkg/sentry/kernel/task_syscall.go:244 +0x10c gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).doSyscall() pkg/sentry/kernel/task_syscall.go:219 +0x1e3 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*runApp).execute() pkg/sentry/kernel/task_run.go:215 +0x15a9 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).run() pkg/sentry/kernel/task_run.go:91 +0x24b Reported-by: syzbot+e1babbf756fab380dfff@syzkaller.appspotmail.com Change-Id: Icd2620bb3ea28b817bf0672d454a22b9d8ee189a PiperOrigin-RevId: 242938741 --- pkg/sentry/fs/dirent.go | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) (limited to 'pkg/sentry') diff --git a/pkg/sentry/fs/dirent.go b/pkg/sentry/fs/dirent.go index 3a1aa6c1e..4870e7d40 100644 --- a/pkg/sentry/fs/dirent.go +++ b/pkg/sentry/fs/dirent.go @@ -1377,15 +1377,14 @@ func (d *Dirent) dropExtendedReference() { // lockForRename takes locks on oldParent and newParent as required by Rename // and returns a function that will unlock the locks taken. The returned // function must be called even if a non-nil error is returned. -// -// Note that lockForRename does not take renameMu if the source and destination -// of the rename are within the same directory. func lockForRename(oldParent *Dirent, oldName string, newParent *Dirent, newName string) (func(), error) { + renameMu.Lock() if oldParent == newParent { - // Rename source and destination are in the same directory. In - // this case, we only need to take a lock on that directory. oldParent.mu.Lock() - return oldParent.mu.Unlock, nil + return func() { + oldParent.mu.Unlock() + renameMu.Unlock() + }, nil } // Renaming between directories is a bit subtle: @@ -1398,7 +1397,6 @@ func lockForRename(oldParent *Dirent, oldName string, newParent *Dirent, newName // lock on the ancestor; to avoid this, ensure we take locks in the same // ancestor-to-descendant order. (Holding renameMu prevents this // relationship from changing.) - renameMu.Lock() // First check if newParent is a descendant of oldParent. child := newParent -- cgit v1.2.3