From 43babef991feedbe2acb77d27254d302ab107fa8 Mon Sep 17 00:00:00 2001 From: Jeremy Allison Date: Sun, 27 Feb 2011 18:16:20 +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/wb_common.c | 17 +++++++++++++++++ source3/client/client.c | 4 +++- source3/client/dnsbrowse.c | 11 +++++++++++ source3/lib/events.c | 8 ++++++++ source3/lib/packet.c | 5 +++++ source3/lib/readline.c | 5 +++++ source3/lib/select.c | 12 ++++++++++++ source3/lib/util_sock.c | 11 +++++++++-- source3/lib/wbclient.c | 9 ++++++++- source3/libaddns/dnssock.c | 5 +++++ source3/libads/cldap.c | 5 +++++ source3/libsmb/nmblib.c | 5 +++++ source3/nmbd/nmbd_packets.c | 24 ++++++++++++++++++++++-- source3/utils/smbfilter.c | 8 ++++++-- source3/winbindd/winbindd.c | 6 ++++++ source3/winbindd/winbindd_dual.c | 7 +++++++ 18 files changed, 149 insertions(+), 8 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/wb_common.c b/nsswitch/wb_common.c index d0dfcb8..75ce585 100644 --- a/nsswitch/wb_common.c +++ b/nsswitch/wb_common.c @@ -240,6 +240,12 @@ static int winbind_named_pipe_sock(const char *dir) switch (errno) { case EINPROGRESS: + + if (fd < 0 || fd >= FD_SETSIZE) { + errno = EBADF; + goto error_out; + } + FD_ZERO(&w_fds); FD_SET(fd, &w_fds); tv.tv_sec = CONNECT_TIMEOUT - wait_time; @@ -384,6 +390,12 @@ int winbind_write_sock(void *buffer, int count, int recursing, int need_priv) struct timeval tv; fd_set r_fds; + if (winbindd_fd < 0 || winbindd_fd >= FD_SETSIZE) { + errno = EBADF; + winbind_close_sock(); + return -1; + } + /* Catch pipe close on other end by checking if a read() call would not block by calling select(). */ @@ -444,6 +456,11 @@ int winbind_read_sock(void *buffer, int count) struct timeval tv; fd_set r_fds; + if (winbindd_fd < 0 || winbindd_fd >= FD_SETSIZE) { + errno = EBADF; + winbind_close_sock(); + return -1; + } /* Catch pipe close on other end by checking if a read() call would not block by calling select(). */ diff --git a/source3/client/client.c b/source3/client/client.c index b706591..1e5e8e1 100644 --- a/source3/client/client.c +++ b/source3/client/client.c @@ -4384,8 +4384,10 @@ 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 90d86c6..3c83f81 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/packet.c b/source3/lib/packet.c index ef28bf9..c14d1e5 100644 --- a/source3/lib/packet.c +++ b/source3/lib/packet.c @@ -106,6 +106,11 @@ 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 da79aca..238daf4 100644 --- a/source3/lib/util_sock.c +++ b/source3/lib/util_sock.c @@ -560,6 +560,11 @@ 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); @@ -1294,7 +1299,7 @@ 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); } @@ -1343,8 +1348,10 @@ 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) diff --git a/source3/lib/wbclient.c b/source3/lib/wbclient.c index 3cf992c..9cb250d 100644 --- a/source3/lib/wbclient.c +++ b/source3/lib/wbclient.c @@ -120,7 +120,7 @@ static bool winbind_closed_fd(int fd) struct timeval tv; fd_set r_fds; - if (fd == -1) { + if (fd == -1 || fd >= FD_SETSIZE) { return true; } @@ -222,6 +222,13 @@ static struct tevent_req *wb_connect_send(TALLOC_CTX *mem_ctx, wbc_err = map_wbc_err_from_errno(errno); goto post_status; } + if (wb_ctx->fd >= FD_SETSIZE) { + close(wb_ctx->fd); + wb_ctx->fd = -1; + errno = EBADF; + wbc_err = map_wbc_err_from_errno(errno); + goto post_status; + } subreq = async_connect_send(mem_ctx, ev, wb_ctx->fd, (struct sockaddr *)&sunaddr, 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/libads/cldap.c b/source3/libads/cldap.c index ae087d9..ac4e2cb 100644 --- a/source3/libads/cldap.c +++ b/source3/libads/cldap.c @@ -134,6 +134,11 @@ static int recv_cldap_netlogon(TALLOC_CTX *mem_ctx, return -1; } + if (sock < 0 || sock >= FD_SETSIZE) { + errno = EBADF; + return -1; + } + FD_ZERO(&r_fds); FD_SET(sock, &r_fds); diff --git a/source3/libsmb/nmblib.c b/source3/libsmb/nmblib.c index 1206d9d..8230c5a 100644 --- a/source3/libsmb/nmblib.c +++ b/source3/libsmb/nmblib.c @@ -1089,6 +1089,11 @@ 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 f69845b..1c570ea 100644 --- a/source3/nmbd/nmbd_packets.c +++ b/source3/nmbd/nmbd_packets.c @@ -1683,7 +1683,7 @@ static bool create_listen_fdset(fd_set **ppset, int **psock_array, int *listen_n for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) count++; - if((count*2) + 2 > FD_SETSIZE) { + if((count*2) + 2 >= FD_SETSIZE) { DEBUG(0,("create_listen_fdset: Too many file descriptors needed (%d). We can \ only use %d.\n", (count*2) + 2, FD_SETSIZE)); SAFE_FREE(pset); @@ -1699,24 +1699,44 @@ only use %d.\n", (count*2) + 2, FD_SETSIZE)); FD_ZERO(pset); /* Add in the broadcast socket 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); /* 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); } /* Add in the broadcast socket 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); /* 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); @@ -1767,7 +1787,7 @@ 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 39a2640..a3ed657 100644 --- a/source3/utils/smbfilter.c +++ b/source3/utils/smbfilter.c @@ -170,8 +170,8 @@ 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; @@ -243,6 +243,10 @@ static void start_filter(char *desthost) struct sockaddr_storage ss; socklen_t in_addrlen = sizeof(ss); + if (s < 0 || s >= FD_SETSIZE) { + break; + } + FD_ZERO(&fds); FD_SET(s, &fds); diff --git a/source3/winbindd/winbindd.c b/source3/winbindd/winbindd.c index 0443ebf..b72d42b 100644 --- a/source3/winbindd/winbindd.c +++ b/source3/winbindd/winbindd.c @@ -1064,6 +1064,12 @@ static void process_loop(void) } for (ev = fd_events; ev; ev = ev->next) { + if (ev->fd < 0 || ev->fd >= FD_SETSIZE) { + /* Ignore here - event_add_to_select_args + should make this impossible. */ + continue; + } + if (ev->flags & EVENT_FD_READ) { FD_SET(ev->fd, &r_fds); maxfd = MAX(ev->fd, maxfd); diff --git a/source3/winbindd/winbindd_dual.c b/source3/winbindd/winbindd_dual.c index 72e5607..3eef3d3 100644 --- a/source3/winbindd/winbindd_dual.c +++ b/source3/winbindd/winbindd_dual.c @@ -1403,6 +1403,13 @@ 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