From cfc784a152ebbc4fc0b8bf13c02e0f6eb9c980bd Mon Sep 17 00:00:00 2001
From: Damien Neil <dneil@google.com>
Date: Thu, 27 Mar 2025 16:22:38 -0700
Subject: os: avoid panic in Root when symlink references the root

We would panic when opening a symlink ending in ..,
where the symlink references the root itself.

Fixes #73081

Change-Id: I7dc3f041ca79df7942feec58c197fde6881ecae5
Reviewed-on: https://go-review.googlesource.com/c/go/+/661416
Reviewed-by: Alan Donovan <adonovan@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
---
 src/os/root_openat.go | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'src/os/root_openat.go')

diff --git a/src/os/root_openat.go b/src/os/root_openat.go
index 6591825648..f67794cd72 100644
--- a/src/os/root_openat.go
+++ b/src/os/root_openat.go
@@ -226,6 +226,9 @@ func doInRoot[T any](r *Root, name string, f func(parent sysfdType, name string)
 				return ret, errPathEscapes
 			}
 			parts = slices.Delete(parts, i-count, end)
+			if len(parts) == 0 {
+				parts = []string{"."}
+			}
 			i = 0
 			if dirfd != rootfd {
 				syscall.Close(dirfd)
-- 
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