Date: Sun, 22 Jul 2018 05:37:58 +0000 (UTC) From: Matt Macy <mmacy@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r336596 - in head/sys/netinet: . cc Message-ID: <201807220537.w6M5bwTh005574@repo.freebsd.org>
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Author: mmacy Date: Sun Jul 22 05:37:58 2018 New Revision: 336596 URL: https://svnweb.freebsd.org/changeset/base/336596 Log: NULL out cc_data in pluggable TCP {cc}_cb_destroy When ABE was added (rS331214) to NewReno and leak fixed (rS333699) , it now has a destructor (newreno_cb_destroy) for per connection state. Other congestion controls may allocate and free cc_data on entry and exit, but the field is never explicitly NULLed if moving back to NewReno which only internally allocates stateful data (no entry contstructor) resulting in a situation where newreno_cb_destory might be called on a junk pointer. - NULL out cc_data in the framework after calling {cc}_cb_destroy - free(9) checks for NULL so there is no need to perform not NULL checks before calling free. - Improve a comment about NewReno in tcp_ccalgounload This is the result of a debugging session from Jason Wolfe, Jason Eggleston, and mmacy@ and very helpful insight from lstewart@. Submitted by: Kevin Bowling Reviewed by: lstewart Sponsored by: Limelight Networks Differential Revision: https://reviews.freebsd.org/D16282 Modified: head/sys/netinet/cc/cc_chd.c head/sys/netinet/cc/cc_cubic.c head/sys/netinet/cc/cc_dctcp.c head/sys/netinet/cc/cc_htcp.c head/sys/netinet/cc/cc_newreno.c head/sys/netinet/cc/cc_vegas.c head/sys/netinet/tcp_subr.c head/sys/netinet/tcp_usrreq.c Modified: head/sys/netinet/cc/cc_chd.c ============================================================================== --- head/sys/netinet/cc/cc_chd.c Sun Jul 22 03:58:01 2018 (r336595) +++ head/sys/netinet/cc/cc_chd.c Sun Jul 22 05:37:58 2018 (r336596) @@ -307,8 +307,7 @@ static void chd_cb_destroy(struct cc_var *ccv) { - if (ccv->cc_data != NULL) - free(ccv->cc_data, M_CHD); + free(ccv->cc_data, M_CHD); } static int Modified: head/sys/netinet/cc/cc_cubic.c ============================================================================== --- head/sys/netinet/cc/cc_cubic.c Sun Jul 22 03:58:01 2018 (r336595) +++ head/sys/netinet/cc/cc_cubic.c Sun Jul 22 05:37:58 2018 (r336596) @@ -213,9 +213,7 @@ cubic_ack_received(struct cc_var *ccv, uint16_t type) static void cubic_cb_destroy(struct cc_var *ccv) { - - if (ccv->cc_data != NULL) - free(ccv->cc_data, M_CUBIC); + free(ccv->cc_data, M_CUBIC); } static int Modified: head/sys/netinet/cc/cc_dctcp.c ============================================================================== --- head/sys/netinet/cc/cc_dctcp.c Sun Jul 22 03:58:01 2018 (r336595) +++ head/sys/netinet/cc/cc_dctcp.c Sun Jul 22 05:37:58 2018 (r336596) @@ -184,8 +184,7 @@ dctcp_after_idle(struct cc_var *ccv) static void dctcp_cb_destroy(struct cc_var *ccv) { - if (ccv->cc_data != NULL) - free(ccv->cc_data, M_dctcp); + free(ccv->cc_data, M_dctcp); } static int Modified: head/sys/netinet/cc/cc_htcp.c ============================================================================== --- head/sys/netinet/cc/cc_htcp.c Sun Jul 22 03:58:01 2018 (r336595) +++ head/sys/netinet/cc/cc_htcp.c Sun Jul 22 05:37:58 2018 (r336596) @@ -238,9 +238,7 @@ htcp_ack_received(struct cc_var *ccv, uint16_t type) static void htcp_cb_destroy(struct cc_var *ccv) { - - if (ccv->cc_data != NULL) - free(ccv->cc_data, M_HTCP); + free(ccv->cc_data, M_HTCP); } static int Modified: head/sys/netinet/cc/cc_newreno.c ============================================================================== --- head/sys/netinet/cc/cc_newreno.c Sun Jul 22 03:58:01 2018 (r336595) +++ head/sys/netinet/cc/cc_newreno.c Sun Jul 22 05:37:58 2018 (r336596) @@ -127,9 +127,7 @@ newreno_malloc(struct cc_var *ccv) static void newreno_cb_destroy(struct cc_var *ccv) { - - if (ccv->cc_data != NULL) - free(ccv->cc_data, M_NEWRENO); + free(ccv->cc_data, M_NEWRENO); } static void Modified: head/sys/netinet/cc/cc_vegas.c ============================================================================== --- head/sys/netinet/cc/cc_vegas.c Sun Jul 22 03:58:01 2018 (r336595) +++ head/sys/netinet/cc/cc_vegas.c Sun Jul 22 05:37:58 2018 (r336596) @@ -170,9 +170,7 @@ vegas_ack_received(struct cc_var *ccv, uint16_t ack_ty static void vegas_cb_destroy(struct cc_var *ccv) { - - if (ccv->cc_data != NULL) - free(ccv->cc_data, M_VEGAS); + free(ccv->cc_data, M_VEGAS); } static int Modified: head/sys/netinet/tcp_subr.c ============================================================================== --- head/sys/netinet/tcp_subr.c Sun Jul 22 03:58:01 2018 (r336595) +++ head/sys/netinet/tcp_subr.c Sun Jul 22 05:37:58 2018 (r336596) @@ -1730,10 +1730,18 @@ tcp_ccalgounload(struct cc_algo *unload_algo) */ if (CC_ALGO(tp) == unload_algo) { tmpalgo = CC_ALGO(tp); - /* NewReno does not require any init. */ - CC_ALGO(tp) = &newreno_cc_algo; if (tmpalgo->cb_destroy != NULL) tmpalgo->cb_destroy(tp->ccv); + CC_DATA(tp) = NULL; + /* + * NewReno may allocate memory on + * demand for certain stateful + * configuration as needed, but is + * coded to never fail on memory + * allocation failure so it is a safe + * fallback. + */ + CC_ALGO(tp) = &newreno_cc_algo; } } INP_WUNLOCK(inp); @@ -1885,6 +1893,7 @@ tcp_discardcb(struct tcpcb *tp) /* Allow the CC algorithm to clean up after itself. */ if (CC_ALGO(tp)->cb_destroy != NULL) CC_ALGO(tp)->cb_destroy(tp->ccv); + CC_DATA(tp) = NULL; #ifdef TCP_HHOOK khelp_destroy_osd(tp->osd); Modified: head/sys/netinet/tcp_usrreq.c ============================================================================== --- head/sys/netinet/tcp_usrreq.c Sun Jul 22 03:58:01 2018 (r336595) +++ head/sys/netinet/tcp_usrreq.c Sun Jul 22 05:37:58 2018 (r336596) @@ -1729,6 +1729,7 @@ unlock_and_done: */ if (CC_ALGO(tp)->cb_destroy != NULL) CC_ALGO(tp)->cb_destroy(tp->ccv); + CC_DATA(tp) = NULL; CC_ALGO(tp) = algo; /* * If something goes pear shaped initialising the new
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