From: Richard Mudgett Date: Wed, 25 May 2011 16:23:11 +0000 (+0000) Subject: Give zombies a safe channel driver to use. X-Git-Tag: 1.8.5-rc1~11^2~81 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=aa64eb10778abb85b7d7bc8bafacfc9d577513b4;p=thirdparty%2Fasterisk.git Give zombies a safe channel driver to use. Recent crashes from zombie channels suggests that they need a safe home to goto. When a masquerade happens, the physical part of the zombie channel is hungup. The hangup normally sets the channel private pointer to NULL. If someone then blindly does a callback to the channel driver, a crash is likely because the private pointer is NULL. The masquerade now sets the channel technology of zombie channels to the kill channel driver. Related to the following issues: (issue #19116) (issue #19310) Review: https://reviewboard.asterisk.org/r/1224/ git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@320796 65c4cc65-6c06-0410-ace0-fbb531ad65f3 --- diff --git a/include/asterisk/channel.h b/include/asterisk/channel.h index 72404574b0..f887ca913d 100644 --- a/include/asterisk/channel.h +++ b/include/asterisk/channel.h @@ -629,6 +629,9 @@ struct ast_channel_tech { int (* cc_callback)(struct ast_channel *inbound, const char *dest, ast_cc_callback_fn callback); }; +/*! Kill the channel channel driver technology descriptor. */ +extern const struct ast_channel_tech ast_kill_tech; + struct ast_epoll_data; /*! diff --git a/main/channel.c b/main/channel.c index 3396baf254..a2b8a4a9e0 100644 --- a/main/channel.c +++ b/main/channel.c @@ -612,6 +612,56 @@ static struct ast_cli_entry cli_channel[] = { AST_CLI_DEFINE(handle_cli_core_show_channeltype, "Give more details on that channel type") }; +static struct ast_frame *kill_read(struct ast_channel *chan) +{ + /* Hangup channel. */ + return NULL; +} + +static struct ast_frame *kill_exception(struct ast_channel *chan) +{ + /* Hangup channel. */ + return NULL; +} + +static int kill_write(struct ast_channel *chan, struct ast_frame *frame) +{ + /* Hangup channel. */ + return -1; +} + +static int kill_fixup(struct ast_channel *oldchan, struct ast_channel *newchan) +{ + /* No problem fixing up the channel. */ + return 0; +} + +static int kill_hangup(struct ast_channel *chan) +{ + chan->tech_pvt = NULL; + return 0; +} + +/*! + * \brief Kill the channel channel driver technology descriptor. + * + * \details + * The purpose of this channel technology is to encourage the + * channel to hangup as quickly as possible. + * + * \note Used by DTMF atxfer and zombie channels. + */ +const struct ast_channel_tech ast_kill_tech = { + .type = "Kill", + .description = "Kill channel (should not see this)", + .capabilities = -1, + .read = kill_read, + .exception = kill_exception, + .write = kill_write, + .fixup = kill_fixup, + .hangup = kill_hangup, +}; + #ifdef CHANNEL_TRACE /*! \brief Destructor for the channel trace datastore */ static void ast_chan_trace_destroy_cb(void *data) @@ -6415,6 +6465,12 @@ int ast_do_masquerade(struct ast_channel *original) goto done; } + /* + * We just hung up the physical side of the channel. Set the + * new zombie to use the kill channel driver for safety. + */ + clonechan->tech = &ast_kill_tech; + /* Mangle the name of the clone channel */ snprintf(zombn, sizeof(zombn), "%s", orig); /* quick, hide the brains! */ __ast_change_name_nolink(clonechan, zombn); diff --git a/main/features.c b/main/features.c index b20d5b41e8..07af47eece 100644 --- a/main/features.c +++ b/main/features.c @@ -469,59 +469,16 @@ struct ast_dial_features { int is_caller; }; -#if defined(ATXFER_NULL_TECH) -static struct ast_frame *null_read(struct ast_channel *chan) -{ - /* Hangup channel. */ - return NULL; -} - -static struct ast_frame *null_exception(struct ast_channel *chan) -{ - /* Hangup channel. */ - return NULL; -} - -static int null_write(struct ast_channel *chan, struct ast_frame *frame) -{ - /* Hangup channel. */ - return -1; -} - -static int null_fixup(struct ast_channel *oldchan, struct ast_channel *newchan) -{ - /* No problem fixing up the channel. */ - return 0; -} - -static int null_hangup(struct ast_channel *chan) -{ - chan->tech_pvt = NULL; - return 0; -} - -static const struct ast_channel_tech null_tech = { - .type = "NULL", - .description = "NULL channel driver for atxfer", - .capabilities = -1, - .read = null_read, - .exception = null_exception, - .write = null_write, - .fixup = null_fixup, - .hangup = null_hangup, -}; -#endif /* defined(ATXFER_NULL_TECH) */ - #if defined(ATXFER_NULL_TECH) /*! * \internal - * \brief Set the channel technology to the NULL technology. + * \brief Set the channel technology to the kill technology. * * \param chan Channel to change technology. * * \return Nothing */ -static void set_null_chan_tech(struct ast_channel *chan) +static void set_kill_chan_tech(struct ast_channel *chan) { int idx; @@ -538,8 +495,8 @@ static void set_null_chan_tech(struct ast_channel *chan) chan->tech_pvt = NULL; } - /* Install the NULL technology and wake up anyone waiting on it. */ - chan->tech = &null_tech; + /* Install the kill technology and wake up anyone waiting on it. */ + chan->tech = &ast_kill_tech; for (idx = 0; idx < AST_MAX_FDS; ++idx) { switch (idx) { case AST_ALERT_FD: @@ -3115,7 +3072,7 @@ static struct ast_channel *feature_request_and_dial(struct ast_channel *caller, * Get rid of caller's physical technology so it is free for * other calls. */ - set_null_chan_tech(caller); + set_kill_chan_tech(caller); #endif /* defined(ATXFER_NULL_TECH) */ } else { /* caller is not hungup so monitor it. */