From c3ad6eb506623435d3d9ce62d6f34ed1c960d4be Mon Sep 17 00:00:00 2001 From: Jeremy Allison Date: Sun, 27 Feb 2011 17:58:06 +0100 Subject: [PATCH] Fix denial of service - memory corruption. CVE-2011-0719 Fix bug #7949 (DoS in Winbind and smbd with many file descriptors open). 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. A connection to a file share, or a local account is needed to exploit this problem, either authenticated or unauthenticated (guest connection). Currently we do not believe this flaw is exploitable beyond a crash or causing the code to loop, but on the advice of our security reviewers we are releasing fixes in case an exploit is discovered at a later date. --- lib/tevent/tevent_select.c | 10 ++++++++++ lib/tevent/tevent_standard.c | 5 +++++ nsswitch/libwbclient/wbc_async.c | 2 +- nsswitch/wb_common.c | 14 ++++++++++++++ source3/client/client.c | 4 +++- source3/client/dnsbrowse.c | 11 +++++++++++ source3/lib/events.c | 8 ++++++++ source3/lib/g_lock.c | 4 +++- source3/lib/packet.c | 5 +++++ source3/lib/readline.c | 5 +++++ source3/lib/select.c | 12 ++++++++++++ source3/lib/util_sock.c | 15 ++++++++++++--- source3/libaddns/dnssock.c | 5 +++++ source3/libsmb/nmblib.c | 5 +++++ source3/nmbd/nmbd_packets.c | 37 +++++++++++++++++++++++++++++++------ source3/utils/smbfilter.c | 7 +++++-- source3/winbindd/winbindd_dual.c | 7 +++++++ 17 files changed, 142 insertions(+), 14 deletions(-) diff --git a/lib/tevent/tevent_select.c b/lib/tevent/tevent_select.c index d974189..890e031 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 c3f8b36..d4a00cc 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 181d546..bb95b91 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 b7fafc3..def41d5 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/source3/client/client.c b/source3/client/client.c index 6d39977..e1952b5 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 5e3a4de..a6b9360 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/lib/events.c b/source3/lib/events.c index 75aa250..63aba58 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 1726047..356c104 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 c131b97..8d815c9 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 34867aa..70a82f2 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 b5443ff..2230b43 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 08cbced..7a573ad 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= 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= 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= 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 7c8bd41..bf11fea 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 cf7023a..c82d4dd 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 a753b28..0eafb2c 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 65d8461..e7abf52 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 44e8552..117d55d 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; -- 1.6.4.2