From 43f5dd95a1c58a6e3260c31093bfc3f97885f4b0 Mon Sep 17 00:00:00 2001 From: Dean Deng Date: Tue, 30 Jun 2020 20:59:32 -0700 Subject: Fix index calculation for /proc/[pid]/cmdline. We were truncating buf using a index relative to the middle of the slice (i.e. where envv begins), but we need to calculate the index relative to the entire slice. Updates #2923. PiperOrigin-RevId: 319154950 --- pkg/sentry/fsimpl/proc/task_files.go | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'pkg') diff --git a/pkg/sentry/fsimpl/proc/task_files.go b/pkg/sentry/fsimpl/proc/task_files.go index 286c23f01..9af43b859 100644 --- a/pkg/sentry/fsimpl/proc/task_files.go +++ b/pkg/sentry/fsimpl/proc/task_files.go @@ -231,8 +231,9 @@ func (d *cmdlineData) Generate(ctx context.Context, buf *bytes.Buffer) error { // Linux will return envp up to and including the first NULL character, // so find it. - if end := bytes.IndexByte(buf.Bytes()[ar.Length():], 0); end != -1 { - buf.Truncate(end) + envStart := int(ar.Length()) + if nullIdx := bytes.IndexByte(buf.Bytes()[envStart:], 0); nullIdx != -1 { + buf.Truncate(envStart + nullIdx) } } @@ -300,7 +301,7 @@ type idMapData struct { var _ dynamicInode = (*idMapData)(nil) -// Generate implements vfs.DynamicBytesSource.Generate. +// Generate implements vfs.WritableDynamicBytesSource.Generate. func (d *idMapData) Generate(ctx context.Context, buf *bytes.Buffer) error { var entries []auth.IDMapEntry if d.gids { @@ -314,6 +315,7 @@ func (d *idMapData) Generate(ctx context.Context, buf *bytes.Buffer) error { return nil } +// Write implements vfs.WritableDynamicBytesSource.Write. func (d *idMapData) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) { // "In addition, the number of bytes written to the file must be less than // the system page size, and the write must be performed at the start of -- cgit v1.2.3