From f263801a74d4ccac042b068d0928c8738e40af5b Mon Sep 17 00:00:00 2001 From: Andrei Vagin Date: Tue, 28 Jan 2020 13:36:16 -0800 Subject: fs/splice: don't report partial errors for special files Special files can have additional requirements for granularity. For example, read from eventfd returns EINVAL if a size is less 8 bytes. Reported-by: syzbot+3905f5493bec08eb7b02@syzkaller.appspotmail.com PiperOrigin-RevId: 292002926 --- pkg/sentry/syscalls/linux/sys_splice.go | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) (limited to 'pkg/sentry/syscalls') diff --git a/pkg/sentry/syscalls/linux/sys_splice.go b/pkg/sentry/syscalls/linux/sys_splice.go index dd3a5807f..f43d6c155 100644 --- a/pkg/sentry/syscalls/linux/sys_splice.go +++ b/pkg/sentry/syscalls/linux/sys_splice.go @@ -211,8 +211,10 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal opts := fs.SpliceOpts{ Length: count, } + inFileAttr := inFile.Dirent.Inode.StableAttr + outFileAttr := outFile.Dirent.Inode.StableAttr switch { - case fs.IsPipe(inFile.Dirent.Inode.StableAttr) && !fs.IsPipe(outFile.Dirent.Inode.StableAttr): + case fs.IsPipe(inFileAttr) && !fs.IsPipe(outFileAttr): if inOffset != 0 { return 0, nil, syserror.ESPIPE } @@ -229,7 +231,7 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal opts.DstOffset = true opts.DstStart = offset } - case !fs.IsPipe(inFile.Dirent.Inode.StableAttr) && fs.IsPipe(outFile.Dirent.Inode.StableAttr): + case !fs.IsPipe(inFileAttr) && fs.IsPipe(outFileAttr): if outOffset != 0 { return 0, nil, syserror.ESPIPE } @@ -246,13 +248,13 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal opts.SrcOffset = true opts.SrcStart = offset } - case fs.IsPipe(inFile.Dirent.Inode.StableAttr) && fs.IsPipe(outFile.Dirent.Inode.StableAttr): + case fs.IsPipe(inFileAttr) && fs.IsPipe(outFileAttr): if inOffset != 0 || outOffset != 0 { return 0, nil, syserror.ESPIPE } // We may not refer to the same pipe; otherwise it's a continuous loop. - if inFile.Dirent.Inode.StableAttr.InodeID == outFile.Dirent.Inode.StableAttr.InodeID { + if inFileAttr.InodeID == outFileAttr.InodeID { return 0, nil, syserror.EINVAL } default: @@ -262,6 +264,15 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal // Splice data. n, err := doSplice(t, outFile, inFile, opts, nonBlock) + // Special files can have additional requirements for granularity. For + // example, read from eventfd returns EINVAL if a size is less 8 bytes. + // Inotify is another example. read will return EINVAL is a buffer is + // too small to return the next event, but a size of an event isn't + // fixed, it is sizeof(struct inotify_event) + {NAME_LEN} + 1. + if n != 0 && err != nil && (fs.IsAnonymous(inFileAttr) || fs.IsAnonymous(outFileAttr)) { + err = nil + } + // See above; inFile is chosen arbitrarily here. return uintptr(n), nil, handleIOError(t, n != 0, err, kernel.ERESTARTSYS, "splice", inFile) } -- cgit v1.2.3