From 4e389c785779114620b47e005d08ca469cc1ed68 Mon Sep 17 00:00:00 2001 From: Dean Deng Date: Wed, 21 Oct 2020 19:15:02 -0700 Subject: Check for nil in kernel.FSContext functions. Reported-by: syzbot+c0e175d2b10708314eb3@syzkaller.appspotmail.com PiperOrigin-RevId: 338386575 --- pkg/sentry/kernel/fs_context.go | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) (limited to 'pkg/sentry') diff --git a/pkg/sentry/kernel/fs_context.go b/pkg/sentry/kernel/fs_context.go index d46d1e1c1..08ea2e09c 100644 --- a/pkg/sentry/kernel/fs_context.go +++ b/pkg/sentry/kernel/fs_context.go @@ -147,19 +147,23 @@ func (f *FSContext) WorkingDirectory() *fs.Dirent { f.mu.Lock() defer f.mu.Unlock() - f.cwd.IncRef() + if f.cwd != nil { + f.cwd.IncRef() + } return f.cwd } // WorkingDirectoryVFS2 returns the current working directory. // -// This will return nil if called after f is destroyed, otherwise it will return -// a Dirent with a reference taken. +// This will return an empty vfs.VirtualDentry if called after f is +// destroyed, otherwise it will return a Dirent with a reference taken. func (f *FSContext) WorkingDirectoryVFS2() vfs.VirtualDentry { f.mu.Lock() defer f.mu.Unlock() - f.cwdVFS2.IncRef() + if f.cwdVFS2.Ok() { + f.cwdVFS2.IncRef() + } return f.cwdVFS2 } @@ -218,13 +222,15 @@ func (f *FSContext) RootDirectory() *fs.Dirent { // RootDirectoryVFS2 returns the current filesystem root. // -// This will return nil if called after f is destroyed, otherwise it will return -// a Dirent with a reference taken. +// This will return an empty vfs.VirtualDentry if called after f is +// destroyed, otherwise it will return a Dirent with a reference taken. func (f *FSContext) RootDirectoryVFS2() vfs.VirtualDentry { f.mu.Lock() defer f.mu.Unlock() - f.rootVFS2.IncRef() + if f.rootVFS2.Ok() { + f.rootVFS2.IncRef() + } return f.rootVFS2 } -- cgit v1.2.3