ksh/ksh-20120801-segfault-strdup.patch

From 9eb8532ccacf1cfdb7ba18f51eba68776852ef7c Mon Sep 17 00:00:00 2001
From: Vincent Mihalkovic <vmihalko@redhat.com>
Date: Thu, 8 Feb 2024 22:10:58 +0100
Subject: [PATCH] Re-fix use of strdup on a NULL pointer (re: 9a9da2c2) (#718)

Thank you @lzaoral for debugging this issue and creating this
reproducer:

$ tty   # check that the shell is connected to a pseudoterminal
/dev/pts/4
$ mkdir /var/tmp/chroottest
$ dnf --releasever=39 --installroot=/var/tmp/chroottest install ksh
$ echo "/dev/udp/127.0.0.1/514;0;104" |
        sudo tee /var/tmp/chroottest/etc/ksh_audit
$ sudo chroot /var/tmp/chroottest /bin/ksh -lic 'exit 0'
(ksh segfaults)

Analysis: On Linux, ttyname(3)[*] may fail if:

* EBADF  Bad file descriptor.
* ENODEV fd refers to a slave pseudoterminal device but the
         corresponding pathname could not be found [...].
* ENOTTY fd does not refer to a terminal device.

Calling isatty(3) before ttyname(3) only prevents the first and
third cases.

src/cmd/ksh93/edit/history.c: sh_histinit():
- To catch the second case, let's call ttyname(2) directly, check
  for NULL and remove the redundant isatty() call.

[*] https://man7.org/linux/man-pages/man3/ttyname.3.html
---
 src/cmd/ksh93/edit/history.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/cmd/ksh93/edit/history.c b/src/cmd/ksh93/edit/history.c
index de5e4a8..222d4bc 100644
--- a/src/cmd/ksh93/edit/history.c
+++ b/src/cmd/ksh93/edit/history.c
@@ -395,7 +395,8 @@ retry:
 			if(fd>=0)
 			{
 				fcntl(fd,F_SETFD,FD_CLOEXEC);
-				hp->tty = strdup(ttyname(2));
+				const char* tty = ttyname(2);
+				hp->tty = strdup(tty?tty:"notty");
 				hp->auditfp = sfnew((Sfio_t*)0,NULL,-1,fd,SF_WRITE);
 			}
 		}
-- 
2.43.0