From: Ian Lance Taylor <iant@golang.org>
Date: Wed, 7 Dec 2022 21:27:22 +0000 (-0800)
Subject: os/user: on AIX getpwuid_r seems to return -1 on overflow
X-Git-Tag: go1.20rc2~1^2~53
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=b9747e0e6b;p=gostls13.git

os/user: on AIX getpwuid_r seems to return -1 on overflow

The getpwuid_r function is expected to return ERANGE on overflow.
Accept -1 on AIX as we see that in practice.

This problem was uncovered by, but not caused by, CL 455815,
which introduced a test that forced a buffer overflow.

Change-Id: I3ae94faf1257d2c73299b1478e49769bb807fc4d
Reviewed-on: https://go-review.googlesource.com/c/go/+/456075
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
---

diff --git a/src/os/user/cgo_lookup_unix.go b/src/os/user/cgo_lookup_unix.go
index b745ffd9cf..3735971eb4 100644
--- a/src/os/user/cgo_lookup_unix.go
+++ b/src/os/user/cgo_lookup_unix.go
@@ -8,6 +8,7 @@ package user
 
 import (
 	"fmt"
+	"runtime"
 	"strconv"
 	"strings"
 	"syscall"
@@ -170,6 +171,9 @@ func retryWithBuffer(startSize bufferKind, f func([]byte) syscall.Errno) error {
 		errno := f(buf)
 		if errno == 0 {
 			return nil
+		} else if runtime.GOOS == "aix" && errno+1 == 0 {
+			// On AIX getpwuid_r appears to return -1,
+			// not ERANGE, on buffer overflow.
 		} else if errno != syscall.ERANGE {
 			return errno
 		}