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Fix the SIGHUP signal race. ed's "event loop" operates a getchar(); check

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the hup flag before and after that call, when the buffer structures are stable
for write_file() to work.  Remove the hup handling from the SPL0() macro,
because this is run in at least one place during structure instability.
The SIGINT handler, which uses siglongjmp(), is also trusting the SPL1/SPL0
dance more than it should.
ok millert
This commit is contained in:
deraadt 2024-07-16 05:01:10 +00:00
parent b9a034e306
commit 2bde29b351
3 changed files with 18 additions and 23 deletions
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6
bin/ed/ed.h
View File

@ -1,4 +1,4 @@
/* $OpenBSD: ed.h,v 1.22 2016/03/27 00:43:38 mmcc Exp $ */
/* $OpenBSD: ed.h,v 1.23 2024/07/16 05:01:10 deraadt Exp $ */
/* $NetBSD: ed.h,v 1.23 1995/03/21 09:04:40 cgd Exp $ */
/* ed.h: type and constant definitions for the ed editor. */
@ -88,8 +88,6 @@ typedef struct undo {
#define SPL0() \
do { \
if (--mutex == 0) { \
if (sighup) \
handle_hup(SIGHUP); \
if (sigint) \
handle_int(SIGINT); \
} \
@ -160,7 +158,7 @@ char *get_extended_line(int *, int);
int get_line_node_addr(line_t *);
char *get_sbuf_line(line_t *);
int get_tty_line(void);
void handle_hup(int);
void handle_hup(void);
void handle_int(int);
int has_trailing_escape(char *, char *);
void init_buffers(void);

10
bin/ed/io.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: io.c,v 1.25 2022/11/18 14:52:03 millert Exp $ */
/* $OpenBSD: io.c,v 1.26 2024/07/16 05:01:10 deraadt Exp $ */
/* $NetBSD: io.c,v 1.2 1995/03/21 09:04:43 cgd Exp $ */
/* io.c: This file contains the i/o routines for the ed line editor */
@ -30,6 +30,7 @@
#include <regex.h>
#include <signal.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@ -261,7 +262,9 @@ get_tty_line(void)
int i = 0;
int c;
for (;;)
for (;;) {
if (sighup)
handle_hup();
switch (c = getchar()) {
default:
oi = 0;
@ -274,6 +277,8 @@ get_tty_line(void)
ibufp = ibuf;
return i;
case EOF:
if (sighup)
handle_hup();
if (ferror(stdin)) {
perror("stdin");
seterrmsg("cannot read stdin");
@ -291,6 +296,7 @@ get_tty_line(void)
return i;
}
}
}
}

25
bin/ed/main.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: main.c,v 1.68 2022/11/18 14:52:03 millert Exp $ */
/* $OpenBSD: main.c,v 1.69 2024/07/16 05:01:10 deraadt Exp $ */
/* $NetBSD: main.c,v 1.3 1995/03/21 09:04:44 cgd Exp $ */
/* main.c: This file contains the main control and user-interface routines
@ -44,6 +44,7 @@
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
#include <ctype.h>
#include <err.h>
@ -180,6 +181,7 @@ top:
signal(SIGWINCH, handle_winch);
}
signal(SIGHUP, signal_hup);
siginterrupt(SIGHUP, 1);
signal(SIGQUIT, SIG_IGN);
signal(SIGINT, signal_int);
if (sigsetjmp(env, 1)) {
@ -1327,45 +1329,34 @@ strip_escapes(char *s)
void
signal_hup(int signo)
{
int save_errno = errno;
if (mutex)
sighup = 1;
else
handle_hup(signo);
errno = save_errno;
sighup = 1;
}
void
signal_int(int signo)
{
int save_errno = errno;
if (mutex)
sigint = 1;
else
handle_int(signo);
errno = save_errno;
handle_int(signo); /* XXX quite unsafe */
}
void
handle_hup(int signo)
handle_hup(void)
{
char hup[PATH_MAX];
if (!sigactive)
quit(1); /* XXX signal race */
signal(SIGHUP, SIG_IGN);
sighup = 0;
/* XXX signal race */
if (addr_last && write_file("ed.hup", "w", 1, addr_last) < 0 &&
home != NULL && home[0] == '/') {
if (strlcpy(hup, home, sizeof(hup)) < sizeof(hup) &&
strlcat(hup, "/ed.hup", sizeof(hup)) < sizeof(hup))
write_file(hup, "w", 1, addr_last);
}
_exit(2);
exit(2);
}