syscall: fix Clearenv on Plan 9

Update #25234 Fixes #35083 Change-Id: Ida39516ab1c14a34a62c2232476a75e83f4e3f75 Reviewed-on: https://go-review.googlesource.com/c/go/+/202657 Reviewed-by: Brad Fitzpatrick <[email protected]>
cloudflare · Oct 23, 2019 · b284dac · b284dac
1 parent 7833302
commit b284dac
Showing 1 changed file with 15 additions and 1 deletion.
diff --git a/src/syscall/env_plan9.go b/src/syscall/env_plan9.go
@@ -74,7 +74,21 @@ func Setenv(key, value string) error {
 }
 
 func Clearenv() {
- RawSyscall(SYS_RFORK, RFCENVG, 0, 0)
+ // Creating a new environment group using rfork(RFCENVG) can race
+ // with access to files in /env (e.g. from Setenv or Getenv).
+ // Remove all environment variables in current environment group instead.
+ fd, err := open("/env", O_RDONLY)
+ if err != nil {
+ return
+ }
+ defer Close(fd)
+ files, err := readdirnames(fd)
+ if err != nil {
+ return
+ }
+ for _, key := range files {
+ Remove("/env/" + key)
+ }
 }
 
 func Unsetenv(key string) error {