ftp.c: improve signal handler restoration
Only invoke the old signal handler if it's a real signal handler and not SIG_IGN, SIG_DFL, SIG_HOLD, or SIG_ERR, using new static function issighandler(). Avoids an intermittent race condition with a null pointer dereference via (*SIG_DFL)(). Bug class reported by Joyu Liao from Juniper Networks. Use SIG_ERR instead of NULL as the indicator that a signal handler hasn't been changed, so that SIG_DFL (equivalent to NULL) will be restored.
This commit is contained in:
lukem
parent
93d38918d6
commit
123e840f8b
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@ -1,4 +1,4 @@
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/* $NetBSD: ftp.c,v 1.169 2020/06/08 01:33:27 lukem Exp $ */
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/* $NetBSD: ftp.c,v 1.170 2020/07/11 02:19:31 lukem Exp $ */
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/*-
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* Copyright (c) 1996-2020 The NetBSD Foundation, Inc.
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@ -92,7 +92,7 @@
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#if 0
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static char sccsid[] = "@(#)ftp.c 8.6 (Berkeley) 10/27/94";
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#else
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__RCSID("$NetBSD: ftp.c,v 1.169 2020/06/08 01:33:27 lukem Exp $");
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__RCSID("$NetBSD: ftp.c,v 1.170 2020/07/11 02:19:31 lukem Exp $");
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#endif
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#endif /* not lint */
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@ -320,6 +320,17 @@ cmdtimeout(int notused)
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errno = oerrno;
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}
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static int
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issighandler(sigfunc func)
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{
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return (func != SIG_IGN &&
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func != SIG_DFL &&
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#ifdef SIG_HOLD
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func != SIG_HOLD &&
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#endif
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func != SIG_ERR);
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}
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/*VARARGS*/
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int
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command(const char *fmt, ...)
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@ -359,8 +370,9 @@ command(const char *fmt, ...)
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(void)fflush(cout);
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cpend = 1;
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r = getreply(!strcmp(fmt, "QUIT"));
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if (abrtflag && oldsigint != SIG_IGN)
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if (abrtflag && issighandler(oldsigint)) {
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(*oldsigint)(SIGINT);
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}
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(void)xsignal(SIGINT, oldsigint);
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return (r);
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}
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@ -510,11 +522,14 @@ getreply(int expecteof)
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(void)xsignal(SIGALRM, oldsigalrm);
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if (code == 421 || originalcode == 421)
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lostpeer(0);
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if (abrtflag && oldsigint != cmdabort && oldsigint != SIG_IGN)
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if (abrtflag && oldsigint != cmdabort &&
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issighandler(oldsigint)) {
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(*oldsigint)(SIGINT);
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}
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if (timeoutflag && oldsigalrm != cmdtimeout &&
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oldsigalrm != SIG_IGN)
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issighandler(oldsigalrm)) {
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(*oldsigalrm)(SIGINT);
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}
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return (n - '0');
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}
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}
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@ -670,7 +685,7 @@ sendrequest(const char *cmd, const char *local, const char *remote,
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FILE *volatile dout;
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int (*volatile closefunc)(FILE *);
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sigfunc volatile oldintr;
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sigfunc volatile oldintp;
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sigfunc volatile oldpipe;
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off_t volatile hashbytes;
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int hash_interval;
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const char *lmode;
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@ -697,8 +712,8 @@ sendrequest(const char *cmd, const char *local, const char *remote,
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if (curtype != type)
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changetype(type, 0);
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closefunc = NULL;
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oldintr = NULL;
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oldintp = NULL;
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oldintr = SIG_ERR;
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oldpipe = SIG_ERR;
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lmode = "w";
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if (sigsetjmp(xferabort, 1)) {
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while (cpend)
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@ -712,7 +727,7 @@ sendrequest(const char *cmd, const char *local, const char *remote,
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fin = stdin;
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progress = 0;
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} else if (*local == '|') {
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oldintp = xsignal(SIGPIPE, SIG_IGN);
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oldpipe = xsignal(SIGPIPE, SIG_IGN);
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fin = popen(local + 1, "r");
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if (fin == NULL) {
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warn("Can't execute `%s'", local + 1);
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@ -786,7 +801,9 @@ sendrequest(const char *cmd, const char *local, const char *remote,
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}
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progressmeter(-1);
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oldintp = xsignal(SIGPIPE, SIG_IGN);
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if (oldpipe == SIG_ERR) {
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oldpipe = xsignal(SIGPIPE, SIG_IGN);
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}
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hash_interval = (hash && (!progress || filesize < 0)) ? mark : 0;
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switch (curtype) {
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@ -855,7 +872,7 @@ sendrequest(const char *cmd, const char *local, const char *remote,
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abort:
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(void)xsignal(SIGINT, oldintr);
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oldintr = NULL;
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oldintr = SIG_ERR;
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if (!cpend) {
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code = -1;
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goto cleanupsend;
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@ -874,10 +891,10 @@ sendrequest(const char *cmd, const char *local, const char *remote,
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ptransfer(0);
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cleanupsend:
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if (oldintr)
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if (oldintr != SIG_ERR)
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(void)xsignal(SIGINT, oldintr);
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if (oldintp)
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(void)xsignal(SIGPIPE, oldintp);
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if (oldpipe != SIG_ERR)
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(void)xsignal(SIGPIPE, oldpipe);
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if (data >= 0) {
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(void)close(data);
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data = -1;
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@ -899,7 +916,7 @@ recvrequest(const char *cmd, const char *volatile local, const char *remote,
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FILE *volatile din;
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int (*volatile closefunc)(FILE *);
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sigfunc volatile oldintr;
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sigfunc volatile oldintp;
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sigfunc volatile oldpipe;
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int c, d;
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int volatile is_retr;
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int volatile tcrflag;
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@ -935,8 +952,8 @@ recvrequest(const char *cmd, const char *volatile local, const char *remote,
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return;
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}
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closefunc = NULL;
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oldintr = NULL;
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oldintp = NULL;
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oldintr = SIG_ERR;
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oldpipe = SIG_ERR;
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tcrflag = !crflag && is_retr;
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if (sigsetjmp(xferabort, 1)) {
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while (cpend)
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@ -1017,7 +1034,7 @@ recvrequest(const char *cmd, const char *volatile local, const char *remote,
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progress = 0;
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preserve = 0;
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} else if (!ignorespecial && *local == '|') {
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oldintp = xsignal(SIGPIPE, SIG_IGN);
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oldpipe = xsignal(SIGPIPE, SIG_IGN);
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fout = popen(local + 1, "w");
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if (fout == NULL) {
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warn("Can't execute `%s'", local+1);
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@ -1183,10 +1200,10 @@ recvrequest(const char *cmd, const char *volatile local, const char *remote,
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ptransfer(0);
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cleanuprecv:
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if (oldintr)
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if (oldintr != SIG_ERR)
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(void)xsignal(SIGINT, oldintr);
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if (oldintp)
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(void)xsignal(SIGPIPE, oldintp);
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if (oldpipe != SIG_ERR)
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(void)xsignal(SIGPIPE, oldpipe);
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if (data >= 0) {
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(void)close(data);
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data = -1;
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@ -1856,7 +1873,7 @@ proxtrans(const char *cmd, const char *local, const char *remote)
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int volatile secndflag;
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const char *volatile cmd2;
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oldintr = NULL;
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oldintr = SIG_ERR;
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secndflag = 0;
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if (strcmp(cmd, "RETR"))
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cmd2 = "RETR";
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@ -1,4 +1,4 @@
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/* $NetBSD: version.h,v 1.89 2020/06/08 01:33:27 lukem Exp $ */
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/* $NetBSD: version.h,v 1.90 2020/07/11 02:19:31 lukem Exp $ */
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/*-
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* Copyright (c) 1999-2020 The NetBSD Foundation, Inc.
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@ -34,5 +34,5 @@
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#endif
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#ifndef FTP_VERSION
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#define FTP_VERSION "20200608"
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#define FTP_VERSION "20200711"
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#endif
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