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authorbubulle <bubulle@alioth.debian.org>2011-03-01 19:31:44 +0000
committerbubulle <bubulle@alioth.debian.org>2011-03-01 19:31:44 +0000
commit9fbd7973837d958b90261b85fafff36ac194ba58 (patch)
tree10a4d232a477fb199033dbd389601a3b754db94d
parentfc9deef5441f504ed1008ce21ed9e12c473f2095 (diff)
downloadsamba-9fbd7973837d958b90261b85fafff36ac194ba58.tar.gz
Load samba-3.5.7 into branches/samba/upstream.upstream/3.5.7
git-svn-id: svn://svn.debian.org/svn/pkg-samba/branches/samba/upstream@3685 fc4039ab-9d04-0410-8cac-899223bdd6b0
-rw-r--r--WHATSNEW.txt53
-rw-r--r--lib/tevent/tevent_select.c10
-rw-r--r--lib/tevent/tevent_standard.c5
-rw-r--r--nsswitch/libwbclient/wbc_async.c2
-rw-r--r--nsswitch/wb_common.c14
-rw-r--r--packaging/RHEL-CTDB/samba.spec2
-rw-r--r--packaging/RHEL/makerpms.sh2
-rw-r--r--packaging/RHEL/samba.spec2
-rw-r--r--source3/VERSION2
-rw-r--r--source3/client/client.c4
-rw-r--r--source3/client/dnsbrowse.c11
-rw-r--r--source3/include/version.h4
-rw-r--r--source3/lib/events.c8
-rw-r--r--source3/lib/g_lock.c4
-rw-r--r--source3/lib/packet.c5
-rw-r--r--source3/lib/readline.c5
-rw-r--r--source3/lib/select.c12
-rw-r--r--source3/lib/util_sock.c15
-rw-r--r--source3/libaddns/dnssock.c5
-rw-r--r--source3/libsmb/nmblib.c5
-rw-r--r--source3/nmbd/nmbd_packets.c37
-rw-r--r--source3/utils/smbfilter.c7
-rw-r--r--source3/winbindd/winbindd_dual.c7
23 files changed, 199 insertions, 22 deletions
diff --git a/WHATSNEW.txt b/WHATSNEW.txt
index aae68e6589..6d6a61c464 100644
--- a/WHATSNEW.txt
+++ b/WHATSNEW.txt
@@ -1,4 +1,53 @@
=============================
+ Release Notes for Samba 3.5.7
+ February 28, 2011
+ =============================
+
+
+This is a security release in order to address CVE-2011-0719.
+
+
+o CVE-2011-0719:
+ All current released versions of Samba are vulnerable to
+ a denial of service caused by memory corruption. Range
+ checks on file descriptors being used in the FD_SET macro
+ were not present allowing stack corruption. This can cause
+ the Samba code to crash or to loop attempting to select
+ on a bad file descriptor set.
+
+
+Changes since 3.5.6:
+--------------------
+
+
+o Jeremy Allison <jra@samba.org>
+ * BUG 7949: Fix DoS in Winbind and smbd with many file descriptors open.
+
+
+######################################################################
+Reporting bugs & Development Discussion
+#######################################
+
+Please discuss this release on the samba-technical mailing list or by
+joining the #samba-technical IRC channel on irc.freenode.net.
+
+If you do report problems then please try to send high quality
+feedback. If you don't provide vital information to help us track down
+the problem then you will probably be ignored. All bug reports should
+be filed under the Samba 3.5 product in the project's Bugzilla
+database (https://bugzilla.samba.org/).
+
+
+======================================================================
+== Our Code, Our Bugs, Our Responsibility.
+== The Samba Team
+======================================================================
+
+
+Release notes for older releases follow:
+----------------------------------------
+
+ =============================
Release Notes for Samba 3.5.6
October 8, 2010
=============================
@@ -94,8 +143,8 @@ database (https://bugzilla.samba.org/).
======================================================================
-Release notes for older releases follow:
-----------------------------------------
+----------------------------------------------------------------------
+
=============================
Release Notes for Samba 3.5.5
diff --git a/lib/tevent/tevent_select.c b/lib/tevent/tevent_select.c
index d97418991a..890e0311c6 100644
--- a/lib/tevent/tevent_select.c
+++ b/lib/tevent/tevent_select.c
@@ -111,6 +111,11 @@ static struct tevent_fd *select_event_add_fd(struct tevent_context *ev, TALLOC_C
struct select_event_context);
struct tevent_fd *fde;
+ if (fd < 0 || fd >= FD_SETSIZE) {
+ errno = EBADF;
+ return NULL;
+ }
+
fde = tevent_common_add_fd(ev, mem_ctx, fd, flags,
handler, private_data,
handler_name, location);
@@ -143,6 +148,11 @@ static int select_event_loop_select(struct select_event_context *select_ev, stru
/* setup any fd events */
for (fde = select_ev->ev->fd_events; fde; fde = fde->next) {
+ if (fde->fd < 0 || fde->fd >= FD_SETSIZE) {
+ errno = EBADF;
+ return -1;
+ }
+
if (fde->flags & TEVENT_FD_READ) {
FD_SET(fde->fd, &r_fds);
}
diff --git a/lib/tevent/tevent_standard.c b/lib/tevent/tevent_standard.c
index c3f8b36e84..d4a00cc062 100644
--- a/lib/tevent/tevent_standard.c
+++ b/lib/tevent/tevent_standard.c
@@ -457,6 +457,11 @@ static int std_event_loop_select(struct std_event_context *std_ev, struct timeva
/* setup any fd events */
for (fde = std_ev->ev->fd_events; fde; fde = fde->next) {
+ if (fde->fd < 0 || fde->fd >= FD_SETSIZE) {
+ std_ev->exit_code = EBADF;
+ return -1;
+ }
+
if (fde->flags & TEVENT_FD_READ) {
FD_SET(fde->fd, &r_fds);
}
diff --git a/nsswitch/libwbclient/wbc_async.c b/nsswitch/libwbclient/wbc_async.c
index 181d5463e9..bb95b91740 100644
--- a/nsswitch/libwbclient/wbc_async.c
+++ b/nsswitch/libwbclient/wbc_async.c
@@ -509,7 +509,7 @@ static bool closed_fd(int fd)
fd_set r_fds;
int selret;
- if (fd == -1) {
+ if (fd < 0 || fd >= FD_SETSIZE) {
return true;
}
diff --git a/nsswitch/wb_common.c b/nsswitch/wb_common.c
index b7fafc38ce..def41d5cea 100644
--- a/nsswitch/wb_common.c
+++ b/nsswitch/wb_common.c
@@ -244,6 +244,10 @@ static int winbind_named_pipe_sock(const char *dir)
switch (errno) {
case EINPROGRESS:
FD_ZERO(&w_fds);
+ if (fd < 0 || fd >= FD_SETSIZE) {
+ errno = EBADF;
+ goto error_out;
+ }
FD_SET(fd, &w_fds);
tv.tv_sec = CONNECT_TIMEOUT - wait_time;
tv.tv_usec = 0;
@@ -391,6 +395,11 @@ int winbind_write_sock(void *buffer, int count, int recursing, int need_priv)
call would not block by calling select(). */
FD_ZERO(&r_fds);
+ if (winbindd_fd < 0 || winbindd_fd >= FD_SETSIZE) {
+ errno = EBADF;
+ winbind_close_sock();
+ return -1;
+ }
FD_SET(winbindd_fd, &r_fds);
ZERO_STRUCT(tv);
@@ -451,6 +460,11 @@ int winbind_read_sock(void *buffer, int count)
call would not block by calling select(). */
FD_ZERO(&r_fds);
+ if (winbindd_fd < 0 || winbindd_fd >= FD_SETSIZE) {
+ errno = EBADF;
+ winbind_close_sock();
+ return -1;
+ }
FD_SET(winbindd_fd, &r_fds);
ZERO_STRUCT(tv);
/* Wait for 5 seconds for a reply. May need to parameterise this... */
diff --git a/packaging/RHEL-CTDB/samba.spec b/packaging/RHEL-CTDB/samba.spec
index ea7057185c..66b13fd460 100644
--- a/packaging/RHEL-CTDB/samba.spec
+++ b/packaging/RHEL-CTDB/samba.spec
@@ -5,7 +5,7 @@ Summary: Samba SMB client and server
Vendor: Samba Team
Packager: Samba Team <samba@samba.org>
Name: samba
-Version: 3.5.6
+Version: 3.5.7
Release: 1GITHASH
Epoch: 0
License: GNU GPL version 3
diff --git a/packaging/RHEL/makerpms.sh b/packaging/RHEL/makerpms.sh
index 0ca37e00b1..fd30afbc58 100644
--- a/packaging/RHEL/makerpms.sh
+++ b/packaging/RHEL/makerpms.sh
@@ -20,7 +20,7 @@ SRCDIR=`rpm --eval %_sourcedir`
USERID=`id -u`
GRPID=`id -g`
-VERSION='3.5.6'
+VERSION='3.5.7'
REVISION=''
SPECFILE="samba.spec"
RPMVER=`rpm --version | awk '{print $3}'`
diff --git a/packaging/RHEL/samba.spec b/packaging/RHEL/samba.spec
index 84118a840e..4fde85ee64 100644
--- a/packaging/RHEL/samba.spec
+++ b/packaging/RHEL/samba.spec
@@ -5,7 +5,7 @@ Summary: Samba SMB client and server
Vendor: Samba Team
Packager: Samba Team <samba@samba.org>
Name: samba
-Version: 3.5.6
+Version: 3.5.7
Release: 1
Epoch: 0
License: GNU GPL version 3
diff --git a/source3/VERSION b/source3/VERSION
index 5490542b67..7cf6b9bed7 100644
--- a/source3/VERSION
+++ b/source3/VERSION
@@ -25,7 +25,7 @@
########################################################
SAMBA_VERSION_MAJOR=3
SAMBA_VERSION_MINOR=5
-SAMBA_VERSION_RELEASE=6
+SAMBA_VERSION_RELEASE=7
########################################################
# Bug fix releases use a letter for the patch revision #
diff --git a/source3/client/client.c b/source3/client/client.c
index 6d399771cb..e1952b593d 100644
--- a/source3/client/client.c
+++ b/source3/client/client.c
@@ -4420,8 +4420,10 @@ static void readline_callback(void)
again:
- if (cli->fd == -1)
+ if (cli->fd < 0 || cli->fd >= FD_SETSIZE) {
+ errno = EBADF;
return;
+ }
FD_ZERO(&fds);
FD_SET(cli->fd,&fds);
diff --git a/source3/client/dnsbrowse.c b/source3/client/dnsbrowse.c
index 5e3a4de9cf..a6b9360a1b 100644
--- a/source3/client/dnsbrowse.c
+++ b/source3/client/dnsbrowse.c
@@ -81,6 +81,11 @@ static void do_smb_resolve(struct mdns_smbsrv_result *browsesrv)
TALLOC_FREE(fdset);
}
+ if (mdnsfd < 0 || mdnsfd >= FD_SETSIZE) {
+ errno = EBADF;
+ break;
+ }
+
fdsetsz = howmany(mdnsfd + 1, NFDBITS) * sizeof(fd_mask);
fdset = TALLOC_ZERO(ctx, fdsetsz);
FD_SET(mdnsfd, fdset);
@@ -181,6 +186,12 @@ int do_smb_browse(void)
TALLOC_FREE(fdset);
}
+ if (mdnsfd < 0 || mdnsfd >= FD_SETSIZE) {
+ errno = EBADF;
+ TALLOC_FREE(ctx);
+ return 1;
+ }
+
fdsetsz = howmany(mdnsfd + 1, NFDBITS) * sizeof(fd_mask);
fdset = TALLOC_ZERO(ctx, fdsetsz);
FD_SET(mdnsfd, fdset);
diff --git a/source3/include/version.h b/source3/include/version.h
index 8e2b35d546..073efa6f38 100644
--- a/source3/include/version.h
+++ b/source3/include/version.h
@@ -1,8 +1,8 @@
/* Autogenerated by script/mkversion.sh */
#define SAMBA_VERSION_MAJOR 3
#define SAMBA_VERSION_MINOR 5
-#define SAMBA_VERSION_RELEASE 6
-#define SAMBA_VERSION_OFFICIAL_STRING "3.5.6"
+#define SAMBA_VERSION_RELEASE 7
+#define SAMBA_VERSION_OFFICIAL_STRING "3.5.7"
#ifdef SAMBA_VERSION_VENDOR_FUNCTION
# define SAMBA_VERSION_STRING SAMBA_VERSION_VENDOR_FUNCTION
#else /* SAMBA_VERSION_VENDOR_FUNCTION */
diff --git a/source3/lib/events.c b/source3/lib/events.c
index 75aa250726..63aba58947 100644
--- a/source3/lib/events.c
+++ b/source3/lib/events.c
@@ -55,6 +55,14 @@ bool event_add_to_select_args(struct tevent_context *ev,
bool ret = false;
for (fde = ev->fd_events; fde; fde = fde->next) {
+ if (fde->fd < 0 || fde->fd >= FD_SETSIZE) {
+ /* We ignore here, as it shouldn't be
+ possible to add an invalid fde->fd
+ but we don't want FD_SET to see an
+ invalid fd. */
+ continue;
+ }
+
if (fde->flags & EVENT_FD_READ) {
FD_SET(fde->fd, read_fds);
ret = true;
diff --git a/source3/lib/g_lock.c b/source3/lib/g_lock.c
index 1726047886..356c104bd1 100644
--- a/source3/lib/g_lock.c
+++ b/source3/lib/g_lock.c
@@ -391,7 +391,9 @@ NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, const char *name,
r_fds = &_r_fds;
FD_ZERO(r_fds);
max_fd = ctdbd_conn_get_fd(conn);
- FD_SET(max_fd, r_fds);
+ if (max_fd >= 0 && max_fd < FD_SETSIZE) {
+ FD_SET(max_fd, r_fds);
+ }
}
#endif
diff --git a/source3/lib/packet.c b/source3/lib/packet.c
index c131b973bc..8d815c9951 100644
--- a/source3/lib/packet.c
+++ b/source3/lib/packet.c
@@ -107,6 +107,11 @@ NTSTATUS packet_fd_read_sync(struct packet_context *ctx,
int res;
fd_set r_fds;
+ if (ctx->fd < 0 || ctx->fd >= FD_SETSIZE) {
+ errno = EBADF;
+ return map_nt_error_from_unix(errno);
+ }
+
FD_ZERO(&r_fds);
FD_SET(ctx->fd, &r_fds);
diff --git a/source3/lib/readline.c b/source3/lib/readline.c
index 34867aad9e..70a82f27ab 100644
--- a/source3/lib/readline.c
+++ b/source3/lib/readline.c
@@ -91,6 +91,11 @@ static char *smb_readline_replacement(const char *prompt, void (*callback)(void)
timeout.tv_sec = 5;
timeout.tv_usec = 0;
+ if (fd < 0 || fd >= FD_SETSIZE) {
+ errno = EBADF;
+ break;
+ }
+
FD_ZERO(&fds);
FD_SET(fd,&fds);
diff --git a/source3/lib/select.c b/source3/lib/select.c
index b5443ff20c..2230b43475 100644
--- a/source3/lib/select.c
+++ b/source3/lib/select.c
@@ -75,6 +75,17 @@ int sys_select(int maxfd, fd_set *readfds, fd_set *writefds, fd_set *errorfds, s
return -1;
}
+ if (select_pipe[0] < 0 || select_pipe[0] >= FD_SETSIZE) {
+ DEBUG(0, ("sys_select: bad fd\n"));
+ if (readfds != NULL)
+ FD_ZERO(readfds);
+ if (writefds != NULL)
+ FD_ZERO(writefds);
+ if (errorfds != NULL)
+ FD_ZERO(errorfds);
+ errno = EBADF;
+ return -1;
+ }
/*
* These next two lines seem to fix a bug with the Linux
* 2.0.x kernel (and probably other UNIXes as well) where
@@ -101,6 +112,7 @@ int sys_select(int maxfd, fd_set *readfds, fd_set *writefds, fd_set *errorfds, s
readfds2 = &readfds_buf;
FD_ZERO(readfds2);
}
+
FD_SET(select_pipe[0], readfds2);
errno = 0;
diff --git a/source3/lib/util_sock.c b/source3/lib/util_sock.c
index 08cbced1e5..7a573ad520 100644
--- a/source3/lib/util_sock.c
+++ b/source3/lib/util_sock.c
@@ -495,6 +495,11 @@ NTSTATUS read_fd_with_timeout(int fd, char *buf,
timeout.tv_usec = (long)(1000 * (time_out % 1000));
for (nread=0; nread < mincnt; ) {
+ if (fd < 0 || fd >= FD_SETSIZE) {
+ errno = EBADF;
+ return map_nt_error_from_unix(EBADF);
+ }
+
FD_ZERO(&fds);
FD_SET(fd,&fds);
@@ -1235,7 +1240,7 @@ bool open_any_socket_out(struct sockaddr_storage *addrs, int num_addrs,
for (i=0; i<num_addrs; i++) {
sockets[i] = socket(addrs[i].ss_family, SOCK_STREAM, 0);
- if (sockets[i] < 0)
+ if (sockets[i] < 0 || sockets[i] >= FD_SETSIZE)
goto done;
set_blocking(sockets[i], false);
}
@@ -1284,8 +1289,10 @@ bool open_any_socket_out(struct sockaddr_storage *addrs, int num_addrs,
FD_ZERO(&r_fds);
for (i=0; i<num_addrs; i++) {
- if (sockets[i] == -1)
+ if (sockets[i] < 0 || sockets[i] >= FD_SETSIZE) {
+ /* This cannot happen - ignore if so. */
continue;
+ }
FD_SET(sockets[i], &wr_fds);
FD_SET(sockets[i], &r_fds);
if (sockets[i]>maxfd)
@@ -1305,8 +1312,10 @@ bool open_any_socket_out(struct sockaddr_storage *addrs, int num_addrs,
for (i=0; i<num_addrs; i++) {
- if (sockets[i] == -1)
+ if (sockets[i] < 0 || sockets[i] >= FD_SETSIZE) {
+ /* This cannot happen - ignore if so. */
continue;
+ }
/* Stevens, Network Programming says that if there's a
* successful connect, the socket is only writable. Upon an
diff --git a/source3/libaddns/dnssock.c b/source3/libaddns/dnssock.c
index 7c8bd418e5..bf11fea931 100644
--- a/source3/libaddns/dnssock.c
+++ b/source3/libaddns/dnssock.c
@@ -219,6 +219,11 @@ static DNS_ERROR read_all(int fd, uint8 *data, size_t len)
ssize_t ret;
int fd_ready;
+ if (fd < 0 || fd >= FD_SETSIZE) {
+ /* read timeout */
+ return ERROR_DNS_SOCKET_ERROR;
+ }
+
FD_ZERO( &rfds );
FD_SET( fd, &rfds );
diff --git a/source3/libsmb/nmblib.c b/source3/libsmb/nmblib.c
index cf7023a9a9..c82d4dd916 100644
--- a/source3/libsmb/nmblib.c
+++ b/source3/libsmb/nmblib.c
@@ -1094,6 +1094,11 @@ struct packet_struct *receive_packet(int fd,enum packet_type type,int t)
struct timeval timeout;
int ret;
+ if (fd < 0 || fd >= FD_SETSIZE) {
+ errno = EBADF;
+ return NULL;
+ }
+
FD_ZERO(&fds);
FD_SET(fd,&fds);
timeout.tv_sec = t/1000;
diff --git a/source3/nmbd/nmbd_packets.c b/source3/nmbd/nmbd_packets.c
index a753b2841d..0eafb2cabe 100644
--- a/source3/nmbd/nmbd_packets.c
+++ b/source3/nmbd/nmbd_packets.c
@@ -1696,7 +1696,7 @@ static bool create_listen_fdset(fd_set **ppset, int **psock_array, int *listen_n
/* each interface gets 4 sockets */
count *= 4;
- if(count > FD_SETSIZE) {
+ if(count >= FD_SETSIZE) {
DEBUG(0,("create_listen_fdset: Too many file descriptors needed (%d). We can \
only use %d.\n", count, FD_SETSIZE));
SAFE_FREE(pset);
@@ -1712,6 +1712,12 @@ only use %d.\n", count, FD_SETSIZE));
FD_ZERO(pset);
/* Add in the lp_socket_address() interface on 137. */
+ if (ClientNMB < 0 || ClientNMB >= FD_SETSIZE) {
+ errno = EBADF;
+ SAFE_FREE(pset);
+ return True;
+ }
+
FD_SET(ClientNMB,pset);
sock_array[num++] = ClientNMB;
*maxfd = MAX( *maxfd, ClientNMB);
@@ -1721,18 +1727,29 @@ only use %d.\n", count, FD_SETSIZE));
/* Add in the 137 sockets on all the interfaces. */
for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
+ if (subrec->nmb_sock < 0 || subrec->nmb_sock >= FD_SETSIZE) {
+ /* We have to ignore sockets outside FD_SETSIZE. */
+ continue;
+ }
FD_SET(subrec->nmb_sock,pset);
sock_array[num++] = subrec->nmb_sock;
*maxfd = MAX( *maxfd, subrec->nmb_sock);
- sock_array[num++] = subrec->nmb_bcast;
- if (subrec->nmb_bcast != -1) {
- FD_SET(subrec->nmb_bcast,pset);
- *maxfd = MAX( *maxfd, subrec->nmb_bcast);
+ if (subrec->nmb_bcast < 0 || subrec->nmb_bcast >= FD_SETSIZE) {
+ /* We have to ignore sockets outside FD_SETSIZE. */
+ continue;
}
+ sock_array[num++] = subrec->nmb_bcast;
+ FD_SET(subrec->nmb_bcast,pset);
+ *maxfd = MAX( *maxfd, subrec->nmb_bcast);
}
/* Add in the lp_socket_address() interface on 138. */
+ if (ClientDGRAM < 0 || ClientDGRAM >= FD_SETSIZE) {
+ errno = EBADF;
+ SAFE_FREE(pset);
+ return True;
+ }
FD_SET(ClientDGRAM,pset);
sock_array[num++] = ClientDGRAM;
*maxfd = MAX( *maxfd, ClientDGRAM);
@@ -1742,10 +1759,18 @@ only use %d.\n", count, FD_SETSIZE));
/* Add in the 138 sockets on all the interfaces. */
for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
+ if (subrec->dgram_sock < 0 || subrec->dgram_sock >= FD_SETSIZE) {
+ /* We have to ignore sockets outside FD_SETSIZE. */
+ continue;
+ }
FD_SET(subrec->dgram_sock,pset);
sock_array[num++] = subrec->dgram_sock;
*maxfd = MAX( *maxfd, subrec->dgram_sock);
+ if (subrec->dgram_bcast < 0 || subrec->dgram_bcast >= FD_SETSIZE) {
+ /* We have to ignore sockets outside FD_SETSIZE. */
+ continue;
+ }
sock_array[num++] = subrec->dgram_bcast;
if (subrec->dgram_bcast != -1) {
FD_SET(subrec->dgram_bcast,pset);
@@ -1876,7 +1901,7 @@ bool listen_for_packets(bool run_election)
#ifndef SYNC_DNS
dns_fd = asyncdns_fd();
- if (dns_fd != -1) {
+ if (dns_fd >= 0 && dns_fd < FD_SETSIZE) {
FD_SET(dns_fd, &r_fds);
maxfd = MAX( maxfd, dns_fd);
}
diff --git a/source3/utils/smbfilter.c b/source3/utils/smbfilter.c
index 65d846124b..e7abf5285e 100644
--- a/source3/utils/smbfilter.c
+++ b/source3/utils/smbfilter.c
@@ -193,8 +193,8 @@ static void filter_child(int c, struct sockaddr_storage *dest_ss)
int num;
FD_ZERO(&fds);
- if (s != -1) FD_SET(s, &fds);
- if (c != -1) FD_SET(c, &fds);
+ if (s >= 0 && s < FD_SETSIZE) FD_SET(s, &fds);
+ if (c >= 0 && c < FD_SETSIZE) FD_SET(c, &fds);
num = sys_select_intr(MAX(s+1, c+1),&fds,NULL,NULL,NULL);
if (num <= 0) continue;
@@ -267,6 +267,9 @@ static void start_filter(char *desthost)
socklen_t in_addrlen = sizeof(ss);
FD_ZERO(&fds);
+ if (s < 0 || s >= FD_SETSIZE) {
+ break;
+ }
FD_SET(s, &fds);
num = sys_select_intr(s+1,&fds,NULL,NULL,NULL);
diff --git a/source3/winbindd/winbindd_dual.c b/source3/winbindd/winbindd_dual.c
index 44e8552e1a..117d55d2da 100644
--- a/source3/winbindd/winbindd_dual.c
+++ b/source3/winbindd/winbindd_dual.c
@@ -1460,6 +1460,13 @@ static bool fork_domain_child(struct winbindd_child *child)
FD_ZERO(&r_fds);
FD_ZERO(&w_fds);
+
+ if (state.sock < 0 || state.sock >= FD_SETSIZE) {
+ TALLOC_FREE(frame);
+ perror("EBADF");
+ _exit(1);
+ }
+
FD_SET(state.sock, &r_fds);
maxfd = state.sock;