merge coverity

--HG--
branch : coverity

.hgsigs

@@ -22,3 +22,4 @@ af074dbcb68ff8670b3818e0d66d5dc6f1bd5877 0 iQIcBAABCgAGBQJWVdQfAAoJEPSYMBLCC7qs+
 fd1981f41c626a969f07b4823848deaefef3c8aa 0 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
 70705edee9dd29cd3d410f19fbd15cc3489313e2 0 iQIcBAABCgAGBQJW7CQRAAoJEESTFJTynGdzTj0QAJL38CKSZthBAeI9c6B+IlwIeT6kPZaPqk1pkycCTWOe87NiNU9abrsF+JrjTuRQiO1EpM2IvfQEIXTijUcMxvld3PnzrZDDv6UvBLtOkn3i++HSVRO0MOuTKI8gFDEPUxRtcaCKXEbqYnf1OTK25FT09Vb//qP9mK1thvlLJmbV+D2a9MkMK66rom1d1h+347IsuwsM+ycHjB80VVAQLA7VYLC5YIwmL17dSmcQLvetfikAMwwmUE+KES4qiLSaqOcAWcKcU67RZzgMMv5o0rESlQmv1nj0mHZtHoUR71sd21emPaRXLOr0oT5YogWUphKq2qVthRn2B06+vd3hPdtn92CmJw9j7zT2jl4OeSjNm9qfAajsRzHIANssFxkGAb7w/LxcMoO29JC+01iUUJMdOVm+4Ns6wGI7qxssWPKdB+VbQUDlHrXLR+sopO524uhkYoWB6DVfTj4R6tImaHtj5/VXON0lsYaLGj8cSH60emL6nNQ0lYV/bSlk6l0s+0x3uXGZnp9oKA+vqMzHfG3vJeMm6KUqtFVjUsYx+q8nHm5/SlWxj1EwnkH8s8ELKZAUXjd76nWEwJ7JFRNRSQWvjOUh3/rsOo4JopzZXPsjCjm+Vql9TG0X6hB21noai32oD5RvfhtR/NX6sXNS5TKZz/j/cMsMnAAsSKb6W7Jm
 9030ffdbe5625e35ed7189ab84a41dfc8d413e9c 0 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
+5c9207ceedaea794f958224c19214d66af6e2d56 0 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

.hgtags

@@ -54,3 +54,4 @@ cbd674d63cd4f3781464a8d4056a5506c8ae926f DROPBEAR_2015.67
 78b12b6549be08b0bea3da329b2578060a76ca31 DROPBEAR_2016.72
 309e1c4a87682b6ca7d80b8555a1db416c3cb7ac DROPBEAR_2016.73
 0ed3d2bbf956cb8a9bf0f4b5a86b7dd9688205cb DROPBEAR_2016.74
+c31276613181c5cff7854e7ef586ace03424e55e DROPBEAR_2017.75

CHANGES

@@ -1,3 +1,28 @@
+2017.75 - 18 May 2017
+
+- Security: Fix double-free in server TCP listener cleanup
+  A double-free in the server could be triggered by an authenticated user if
+  dropbear is running with -a (Allow connections to forwarded ports from any host)
+  This could potentially allow arbitrary code execution as root by an authenticated user.
+  Affects versions 2013.56 to 2016.74. Thanks to Mark Shepard for reporting the crash.
+
+- Security: Fix information disclosure with ~/.ssh/authorized_keys symlink.
+  Dropbear parsed authorized_keys as root, even if it were a symlink. The fix
+  is to switch to user permissions when opening authorized_keys
+
+  A user could symlink their ~/.ssh/authorized_keys to a root-owned file they
+  couldn't normally read. If they managed to get that file to contain valid
+  authorized_keys with command= options it might be possible to read other
+  contents of that file.
+  This information disclosure is to an already authenticated user.
+  Thanks to Jann Horn of Google Project Zero for reporting this.
+
+- Generate hostkeys with dropbearkey atomically and flush to disk with fsync
+  Thanks to Andrei Gherzan for a patch
+
+- Fix out of tree builds with bundled libtom
+  Thanks to Henrik Nordström and Peter Krefting for patches.
+
 2016.74 - 21 July 2016
 
 - Security: Message printout was vulnerable to format string injection.
@@ -9,16 +34,24 @@
   A dbclient user who can control username or host arguments could potentially
   run arbitrary code as the dbclient user. This could be a problem if scripts
   or webpages pass untrusted input to the dbclient program.
+  CVE-2016-7406
+  https://secure.ucc.asn.au/hg/dropbear/rev/b66a483f3dcb
 
 - Security: dropbearconvert import of OpenSSH keys could run arbitrary code as
   the local dropbearconvert user when parsing malicious key files
+  CVE-2016-7407
+  https://secure.ucc.asn.au/hg/dropbear/rev/34e6127ef02e
 
 - Security: dbclient could run arbitrary code as the local dbclient user if
   particular -m or -c arguments are provided. This could be an issue where
   dbclient is used in scripts.
+  CVE-2016-7408
+  https://secure.ucc.asn.au/hg/dropbear/rev/eed9376a4ad6
 
 - Security: dbclient or dropbear server could expose process memory to the
   running user if compiled with DEBUG_TRACE and running with -v
+  CVE-2016-7409
+  https://secure.ucc.asn.au/hg/dropbear/rev/6a14b1f6dc04
 
   The security issues were reported by an anonymous researcher working with
   Beyond Security's SecuriTeam Secure Disclosure www.beyondsecurity.com/ssd.html
@@ -64,6 +97,7 @@
 
 - Validate X11 forwarding input. Could allow bypass of authorized_keys command= restrictions,
   found by github.com/tintinweb. Thanks for Damien Miller for a patch. CVE-2016-3116
+  https://secure.ucc.asn.au/hg/dropbear/rev/a3e8389e01ff
 
 2015.71 - 3 December 2015
 
@@ -342,9 +376,11 @@ kernels, from Steve Dover
 - Limit the size of decompressed payloads, avoids memory exhaustion denial
   of service 
   Thanks to Logan Lamb for reporting and investigating it. CVE-2013-4421
+  https://secure.ucc.asn.au/hg/dropbear/rev/0bf76f54de6f
 
 - Avoid disclosing existence of valid users through inconsistent delays
   Thanks to Logan Lamb for reporting. CVE-2013-4434
+  https://secure.ucc.asn.au/hg/dropbear/rev/d7784616409a
 
 - Update config.guess and config.sub for newer architectures
 
@@ -447,6 +483,7 @@ though probably will be soon
   This bug affects releases 0.52 onwards. Ref CVE-2012-0920.
   Thanks to Danny Fullerton of Mantor Organization for reporting
   the bug.
+  https://secure.ucc.asn.au/hg/dropbear/rev/818108bf7749
 
 - Compile fix, only apply IPV6 socket options if they are available in headers
   Thanks to Gustavo Zacarias for the patch

atomicio.c

@@ -1,6 +1,8 @@
+/* $OpenBSD: atomicio.c,v 1.17 2006/04/01 05:51:34 djm Exp $ */
 /*
- * Copied from OpenSSH 3.6.1p2.
+ * Copied from OpenSSH/OpenBSD.
  * 
+ * Copyright (c) 2005 Anil Madhavapeddy. All rights reserved.
  * Copyright (c) 1995,1999 Theo de Raadt.  All rights reserved.
  * All rights reserved.
  *
@@ -25,39 +27,32 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-/* RCSID("OpenBSD: atomicio.c,v 1.10 2001/05/08 22:48:07 markus Exp "); */
+#include "includes.h"
 
 #include "atomicio.h"
 
 /*
- * ensure all of data on socket comes through. f==read || f==write
+ * ensure all of data on socket comes through. f==read || f==vwrite
  */
-ssize_t
-atomicio(f, fd, _s, n)
-	ssize_t (*f) ();
-	int fd;
-	void *_s;
-	size_t n;
+size_t
+atomicio(ssize_t (*f) (int, void *, size_t), int fd, void *_s, size_t n)
 {
 	char *s = _s;
-	ssize_t res;
 	size_t pos = 0;
+	ssize_t res;
 
 	while (n > pos) {
 		res = (f) (fd, s + pos, n - pos);
 		switch (res) {
 		case -1:
-#ifdef EWOULDBLOCK
-			if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)
-#else
 			if (errno == EINTR || errno == EAGAIN)
-#endif
 				continue;
-			/* FALLTHROUGH */
+			return 0;
 		case 0:
-			return (res);
+			errno = EPIPE;
+			return pos;
 		default:
-			pos += res;
+			pos += (size_t)res;
 		}
 	}
 	return (pos);

atomicio.h

@@ -1,8 +1,7 @@
+/* $OpenBSD: atomicio.h,v 1.7 2006/03/25 22:22:42 djm Exp $ */
 
 /*
- * Copied from OpenSSH 3.6.1p2, required for loginrec.c
- *
- * $OpenBSD: atomicio.h,v 1.4 2001/06/26 06:32:46 itojun Exp $
+ * Copied from OpenSSH/OpenBSD, required for loginrec.c
  *
  * Copyright (c) 1995,1999 Theo de Raadt.  All rights reserved.
  * All rights reserved.
@@ -28,9 +27,9 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include "includes.h"
-
 /*
- * Ensure all of data on socket comes through. f==read || f==write
+ * Ensure all of data on socket comes through. f==read || f==vwrite
  */
-ssize_t	atomicio(ssize_t (*)(), int, void *, size_t);
+size_t	atomicio(ssize_t (*)(int, void *, size_t), int, void *, size_t);
+
+#define vwrite (ssize_t (*)(int, void *, size_t))write

buffer.c

@@ -109,6 +109,7 @@ void buf_setlen(buffer* buf, unsigned int len) {
 		dropbear_exit("Bad buf_setlen");
 	}
 	buf->len = len;
+	buf->pos = MIN(buf->pos, buf->len);
 }
 
 /* Increment the length of the buffer */

cli-agentfwd.c

@@ -130,7 +130,7 @@ static buffer * agent_request(unsigned char type, buffer *data) {
 	}
 	buf_setpos(payload, 0);
 
-	ret = atomicio(write, fd, buf_getptr(payload, payload->len), payload->len);
+	ret = atomicio(vwrite, fd, buf_getptr(payload, payload->len), payload->len);
 	if ((size_t)ret != payload->len) {
 		TRACE(("write failed fd %d for agent_request, %s", fd, strerror(errno)))
 		goto out;

cli-tcpfwd.c

@@ -234,7 +234,7 @@ static int newtcpforwarded(struct Channel * channel) {
 	char *origaddr = NULL;
 	unsigned int origport;
 	m_list_elem * iter = NULL;
-	struct TCPFwdEntry *fwd;
+	struct TCPFwdEntry *fwd = NULL;
 	char portstring[NI_MAXSERV];
 	int err = SSH_OPEN_ADMINISTRATIVELY_PROHIBITED;
 
@@ -265,7 +265,7 @@ static int newtcpforwarded(struct Channel * channel) {
 	}
 
 
-	if (iter == NULL) {
+	if (iter == NULL || fwd == NULL) {
 		/* We didn't request forwarding on that port */
 		cleantext(origaddr);
 		dropbear_log(LOG_INFO, "Server sent unrequested forward from \"%s:%d\"", 

common-channel.c

@@ -32,7 +32,6 @@
 #include "circbuffer.h"
 #include "dbutil.h"
 #include "channel.h"
-#include "ssh.h"
 #include "listener.h"
 #include "runopts.h"
 #include "netio.h"

compat.c

@@ -114,8 +114,8 @@ size_t strlcpy(char *dst, const char *src, size_t size) {
 #endif /* HAVE_STRLCPY */
 
 #ifndef HAVE_STRLCAT
-/* taken from openbsd-compat for OpenSSH 3.6.1p1 */
-/* "$OpenBSD: strlcat.c,v 1.8 2001/05/13 15:40:15 deraadt Exp $"
+/* taken from openbsd-compat for OpenSSH 7.2p2 */
+/* "$OpenBSD: strlcat.c,v 1.13 2005/08/08 08:05:37 espie Exp $"
  *
  * Appends src to string dst of size siz (unlike strncat, siz is the
  * full size of dst, not space left).  At most siz-1 characters
@@ -123,15 +123,12 @@ size_t strlcpy(char *dst, const char *src, size_t size) {
  * Returns strlen(src) + MIN(siz, strlen(initial dst)).
  * If retval >= siz, truncation occurred.
  */
-	size_t
-strlcat(dst, src, siz)
-	char *dst;
-	const char *src;
-	size_t siz;
+size_t
+strlcat(char *dst, const char *src, size_t siz)
 {
-	register char *d = dst;
-	register const char *s = src;
-	register size_t n = siz;
+	char *d = dst;
+	const char *s = src;
+	size_t n = siz;
 	size_t dlen;
 
 	/* Find the end of dst and adjust bytes left but don't go past end */

dbutil.c

@@ -182,7 +182,7 @@ static double time_since_start()
 void dropbear_trace(const char* format, ...) {
 	va_list param;
 
-	if (!ses.debug_trace) {
+	if (!debug_trace) {
 		return;
 	}
 
@@ -681,4 +681,21 @@ time_t monotonic_now() {
 	return time(NULL);
 }
 
+void fsync_parent_dir(const char* fn) {
+#ifdef HAVE_LIBGEN_H
+	char *fn_dir = m_strdup(fn);
+	char *dir = dirname(fn_dir);
+	int dirfd = open(dir, O_RDONLY);
 
+	if (dirfd != -1) {
+		if (fsync(dirfd) != 0) {
+			TRACE(("fsync of directory %s failed: %s", dir, strerror(errno)))
+		}
+		m_close(dirfd);
+	} else {
+		TRACE(("error opening directory %s for fsync: %s", dir, strerror(errno)))
+	}
+
+	free(fn_dir);
+#endif
+}

dbutil.h

@@ -89,4 +89,6 @@ time_t monotonic_now(void);
 
 char * expand_homedir_path(const char *inpath);
 
+void fsync_parent_dir(const char* fn);
+
 #endif /* DROPBEAR_DBUTIL_H_ */

debian/changelog

@@ -1,3 +1,9 @@
+dropbear (2017.75-0.1) unstable; urgency=low
+
+  * New upstream release.
+
+ -- Matt Johnston <matt@ucc.asn.au>  Thu, 18 May 2017 22:51:57 +0800
+
 dropbear (2016.74-0.1) unstable; urgency=low
 
   * New upstream release.

dropbearkey.c

@@ -241,7 +241,7 @@ int main(int argc, char ** argv) {
 	}
 
 	fprintf(stderr, "Generating key, this may take a while...\n");
-	if (signkey_generate(keytype, bits, filename) == DROPBEAR_FAILURE)
+	if (signkey_generate(keytype, bits, filename, 0) == DROPBEAR_FAILURE)
 	{
 		dropbear_exit("Failed to generate key.\n");
 	}

gensignkey.c

@@ -76,10 +76,12 @@ static int get_default_bits(enum signkey_type keytype)
 	}
 }
 
-int signkey_generate(enum signkey_type keytype, int bits, const char* filename)
+/* if skip_exist is set it will silently return if the key file exists */
+int signkey_generate(enum signkey_type keytype, int bits, const char* filename, int skip_exist)
 {
 	sign_key * key = NULL;
 	buffer *buf = NULL;
+	char *fn_temp = NULL;
 	int ret = DROPBEAR_FAILURE;
 	if (bits == 0)
 	{
@@ -126,10 +128,37 @@ int signkey_generate(enum signkey_type keytype, int bits, const char* filename)
 	sign_key_free(key);
 	key = NULL;
 	buf_setpos(buf, 0);
-	ret = buf_writefile(buf, filename);
 
-	buf_burn(buf);
-	buf_free(buf);
-	buf = NULL;
+	fn_temp = m_malloc(strlen(filename) + 30);
+	snprintf(fn_temp, strlen(filename)+30, "%s.tmp%d", filename, getpid());
+	ret = buf_writefile(buf, fn_temp);
+
+	if (ret == DROPBEAR_FAILURE) {
+		goto out;
+	}
+
+	if (link(fn_temp, filename) < 0) {
+		/* If generating keys on connection (skipexist) it's OK to get EEXIST 
+		- we probably just lost a race with another connection to generate the key */
+		if (!(skip_exist && errno == EEXIST)) {
+			dropbear_log(LOG_ERR, "Failed moving key file to %s: %s", filename,
+				strerror(errno));
+			/* XXX fallback to non-atomic copy for some filesystems? */
+			ret = DROPBEAR_FAILURE;
+			goto out;
+		}
+	}
+
+out:
+	if (buf) {
+		buf_burn(buf);
+		buf_free(buf);
+	}
+	
+	if (fn_temp) {
+		unlink(fn_temp);
+		m_free(fn_temp);
+	}
+
 	return ret;
 }

gensignkey.h

@@ -3,6 +3,6 @@
 
 #include "signkey.h"
 
-int signkey_generate(enum signkey_type type, int bits, const char* filename);
+int signkey_generate(enum signkey_type type, int bits, const char* filename, int skip_exist);
 
 #endif

libtomcrypt/Makefile.in

@@ -19,7 +19,7 @@ srcdir=@srcdir@
 
 # Compilation flags. Note the += does not write over the user's CFLAGS!
 # The rest of the flags come from the parent Dropbear makefile
-CFLAGS += -c -I$(srcdir)/src/headers/ -I$(srcdir)/../ -DLTC_SOURCE -I$(srcdir)/../libtommath/
+CFLAGS += -c -Isrc/headers/ -I$(srcdir)/src/headers/ -I../ -I$(srcdir)/../ -DLTC_SOURCE -I../libtommath/ -I$(srcdir)/../libtommath/
 
 # additional warnings (newer GCC 3.4 and higher)
 ifdef GCC_34

libtommath/Makefile.in

@@ -9,7 +9,7 @@ VPATH=@srcdir@
 srcdir=@srcdir@
 
 # So that libtommath can include Dropbear headers for options and m_burn()
-CFLAGS += -I$(srcdir)/../libtomcrypt/src/headers/ -I$(srcdir)/../
+CFLAGS += -I. -I$(srcdir) -I../libtomcrypt/src/headers/ -I$(srcdir)/../libtomcrypt/src/headers/ -I../ -I$(srcdir)/../
 
 ifndef IGNORE_SPEED
 

loginrec.c

@@ -706,7 +706,7 @@ utmp_write_direct(struct logininfo *li, struct utmp *ut)
 		}
 
 		(void)lseek(fd, (off_t)(tty * sizeof(struct utmp)), SEEK_SET);
-		if (atomicio(write, fd, ut, sizeof(*ut)) != sizeof(*ut))
+		if (atomicio(vwrite, fd, ut, sizeof(*ut)) != sizeof(*ut))
 			dropbear_log(LOG_WARNING, "utmp_write_direct: error writing %s: %s",
 			    UTMP_FILE, strerror(errno));
 
@@ -895,7 +895,7 @@ wtmp_write(struct logininfo *li, struct utmp *ut)
 		return 0;
 	}
 	if (fstat(fd, &buf) == 0)
-		if (atomicio(write, fd, ut, sizeof(*ut)) != sizeof(*ut)) {
+		if (atomicio(vwrite, fd, ut, sizeof(*ut)) != sizeof(*ut)) {
 			ftruncate(fd, buf.st_size);
 			dropbear_log(LOG_WARNING, "wtmp_write: problem writing %s: %s",
 			    WTMP_FILE, strerror(errno));
@@ -1062,7 +1062,7 @@ wtmpx_write(struct logininfo *li, struct utmpx *utx)
 	}
 
 	if (fstat(fd, &buf) == 0)
-		if (atomicio(write, fd, utx, sizeof(*utx)) != sizeof(*utx)) {
+		if (atomicio(vwrite, fd, utx, sizeof(*utx)) != sizeof(*utx)) {
 			ftruncate(fd, buf.st_size);
 			dropbear_log(LOG_WARNING, "wtmpx_write: problem writing %s: %s",
 			    WTMPX_FILE, strerror(errno));
@@ -1351,7 +1351,7 @@ lastlog_perform_login(struct logininfo *li)
 		return(0);
 
 	/* write the entry */
-	if (atomicio(write, fd, &last, sizeof(last)) != sizeof(last)) {
+	if (atomicio(vwrite, fd, &last, sizeof(last)) != sizeof(last)) {
 		close(fd);
 		dropbear_log(LOG_WARNING, "lastlog_write_filemode: Error writing to %s: %s",
 		    LASTLOG_FILE, strerror(errno));

scpmisc.h

@@ -12,9 +12,6 @@
  * called by a name other than "ssh" or "Secure Shell".
  */
 
-/* actually from atomicio, but is only used in scp code */
-#define vwrite (ssize_t (*)(int, void *, size_t))write
-
 char	*chop(char *);
 char	*strdelim(char **);
 void	 set_nonblock(int);

svr-authpubkey.c

@@ -201,6 +201,8 @@ static int checkpubkey(char* algo, unsigned int algolen,
 	unsigned int len, pos;
 	buffer * options_buf = NULL;
 	int line_num;
+	uid_t origuid;
+	gid_t origgid;
 
 	TRACE(("enter checkpubkey"))
 
@@ -227,8 +229,21 @@ static int checkpubkey(char* algo, unsigned int algolen,
 	snprintf(filename, len + 22, "%s/.ssh/authorized_keys", 
 				ses.authstate.pw_dir);
 
-	/* open the file */
+	/* open the file as the authenticating user. */
+	origuid = getuid();
+	origgid = getgid();
+	if ((setegid(ses.authstate.pw_gid)) < 0 ||
+		(seteuid(ses.authstate.pw_uid)) < 0) {
+		dropbear_exit("Failed to set euid");
+	}
+
 	authfile = fopen(filename, "r");
+
+	if ((seteuid(origuid)) < 0 ||
+		(setegid(origgid)) < 0) {
+		dropbear_exit("Failed to revert euid");
+	}
+
 	if (authfile == NULL) {
 		goto out;
 	}

svr-authpubkeyoptions.c

@@ -95,6 +95,7 @@ void svr_pubkey_set_forced_command(struct ChanSess *chansess) {
 		if (chansess->cmd) {
 			/* original_command takes ownership */
 			chansess->original_command = chansess->cmd;
+			chansess->cmd = NULL;
 		} else {
 			chansess->original_command = m_strdup("");
 		}
@@ -108,6 +109,9 @@ void svr_pubkey_set_forced_command(struct ChanSess *chansess) {
 /* Free potential public key options */
 void svr_pubkey_options_cleanup() {
 	if (ses.authstate.pubkey_options) {
+		if (ses.authstate.pubkey_options->forced_command) {
+			m_free(ses.authstate.pubkey_options->forced_command);
+		}
 		m_free(ses.authstate.pubkey_options);
 		ses.authstate.pubkey_options = NULL;
 	}
@@ -200,8 +204,7 @@ next_option:
 
 bad_option:
 	ret = DROPBEAR_FAILURE;
-	m_free(ses.authstate.pubkey_options);
-	ses.authstate.pubkey_options = NULL;
+	svr_pubkey_options_cleanup();
 	dropbear_log(LOG_WARNING, "Bad public key options at %s:%d", filename, line_num);
 
 end:

svr-chansession.c

@@ -634,7 +634,7 @@ static void make_connection_string(struct ChanSess *chansess) {
 static int sessioncommand(struct Channel *channel, struct ChanSess *chansess,
 		int iscmd, int issubsys) {
 
-	unsigned int cmdlen;
+	unsigned int cmdlen = 0;
 	int ret;
 
 	TRACE(("enter sessioncommand"))

svr-kex.c

@@ -93,29 +93,9 @@ void recv_msg_kexdh_init() {
 
 #if DROPBEAR_DELAY_HOSTKEY
 
-static void fsync_parent_dir(const char* fn) {
-#ifdef HAVE_LIBGEN_H
-	char *fn_dir = m_strdup(fn);
-	char *dir = dirname(fn_dir);
-	int dirfd = open(dir, O_RDONLY);
-
-	if (dirfd != -1) {
-		if (fsync(dirfd) != 0) {
-			TRACE(("fsync of directory %s failed: %s", dir, strerror(errno)))
-		}
-		m_close(dirfd);
-	} else {
-		TRACE(("error opening directory %s for fsync: %s", dir, strerror(errno)))
-	}
-
-	free(fn_dir);
-#endif
-}
-
 static void svr_ensure_hostkey() {
 
 	const char* fn = NULL;
-	char *fn_temp = NULL;
 	enum signkey_type type = ses.newkeys->algo_hostkey;
 	void **hostkey = signkey_key_ptr(svr_opts.hostkey, type);
 	int ret = DROPBEAR_FAILURE;
@@ -151,28 +131,10 @@ static void svr_ensure_hostkey() {
 		return;
 	}
 
-	fn_temp = m_malloc(strlen(fn) + 20);
-	snprintf(fn_temp, strlen(fn)+20, "%s.tmp%d", fn, getpid());
-
-	if (signkey_generate(type, 0, fn_temp) == DROPBEAR_FAILURE) {
+	if (signkey_generate(type, 0, fn, 1) == DROPBEAR_FAILURE) {
 		goto out;
 	}
-
-	if (link(fn_temp, fn) < 0) {
-		/* It's OK to get EEXIST - we probably just lost a race
-		with another connection to generate the key */
-		if (errno != EEXIST) {
-			dropbear_log(LOG_ERR, "Failed moving key file to %s: %s", fn,
-				strerror(errno));
-			/* XXX fallback to non-atomic copy for some filesystems? */
-			goto out;
-		}
-	}
-
-	/* ensure directory update is flushed to disk, otherwise we can end up
-	with zero-byte hostkey files if the power goes off */
-	fsync_parent_dir(fn);
-
+	
 	ret = readhostkey(fn, svr_opts.hostkey, &type);
 
 	if (ret == DROPBEAR_SUCCESS) {
@@ -190,11 +152,6 @@ static void svr_ensure_hostkey() {
 	}
 
 out:
-	if (fn_temp) {
-		unlink(fn_temp);
-		m_free(fn_temp);
-	}
-
 	if (ret == DROPBEAR_FAILURE)
 	{
 		dropbear_exit("Couldn't read or generate hostkey %s", fn);

svr-tcpfwd.c

@@ -199,7 +199,7 @@ static int svr_remotetcpreq() {
 	}
 	else
 	{
-		tcpinfo->listenaddr = request_addr;
+		tcpinfo->listenaddr = m_strdup(request_addr);
 	}
 
 	ret = listen_tcpfwd(tcpinfo);

sysoptions.h

@@ -4,7 +4,7 @@
  *******************************************************************/
 
 #ifndef DROPBEAR_VERSION
-#define DROPBEAR_VERSION "2016.74"
+#define DROPBEAR_VERSION "2017.75"
 #endif
 
 #define LOCAL_IDENT "SSH-2.0-dropbear_" DROPBEAR_VERSION