Mercurial > hg > nginx-quic
view auto/types/typedef @ 6359:dac6eda40475 stable-1.8
Resolver: fixed use-after-free memory accesses with CNAME.
When several requests were waiting for a response, then after getting
a CNAME response only the last request's context had the name updated.
Contexts of other requests had the wrong name. This name was used by
ngx_resolve_name_done() to find the node to remove the request context
from. When the name was wrong, the request could not be properly
cancelled, its context was freed but stayed linked to the node's waiting
list. This happened e.g. when the first request was aborted or timed
out before the resolving completed. When it completed, this triggered
a use-after-free memory access by calling ctx->handler of already freed
request context. The bug manifests itself by
"could not cancel <name> resolving" alerts in error_log.
When a request was responded with a CNAME, the request context kept
the pointer to the original node's rn->u.cname. If the original node
expired before the resolving timed out or completed with an error,
this would trigger a use-after-free memory access via ctx->name in
ctx->handler().
The fix is to keep ctx->name unmodified. The name from context
is no longer used by ngx_resolve_name_done(). Instead, we now keep
the pointer to resolver node to which this request is linked.
Keeping the original name intact also improves logging.
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Tue, 26 Jan 2016 16:46:59 +0300 |
parents | 434548349838 |
children | 82a76258a142 |
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# Copyright (C) Igor Sysoev # Copyright (C) Nginx, Inc. echo $ngx_n "checking for $ngx_type ...$ngx_c" cat << END >> $NGX_AUTOCONF_ERR ---------------------------------------- checking for $ngx_type END ngx_found=no for ngx_try in $ngx_type $ngx_types do cat << END > $NGX_AUTOTEST.c #include <sys/types.h> #include <signal.h> #include <sys/socket.h> #include <sys/time.h> #include <sys/resource.h> #include <netinet/in.h> $NGX_INCLUDE_INTTYPES_H int main() { $ngx_try i = 0; return (int) i; } END ngx_test="$CC $CC_TEST_FLAGS $CC_AUX_FLAGS \ -o $NGX_AUTOTEST $NGX_AUTOTEST.c $NGX_LD_OPT $ngx_feature_libs" eval "$ngx_test >> $NGX_AUTOCONF_ERR 2>&1" if [ -x $NGX_AUTOTEST ]; then if [ $ngx_try = $ngx_type ]; then echo " found" ngx_found=yes else echo ", $ngx_try used" ngx_found=$ngx_try fi fi rm -rf $NGX_AUTOTEST* if [ $ngx_found = no ]; then echo $ngx_n " $ngx_try not found$ngx_c" echo "----------" >> $NGX_AUTOCONF_ERR cat $NGX_AUTOTEST.c >> $NGX_AUTOCONF_ERR echo "----------" >> $NGX_AUTOCONF_ERR echo $ngx_test >> $NGX_AUTOCONF_ERR echo "----------" >> $NGX_AUTOCONF_ERR else break fi done if [ $ngx_found = no ]; then echo echo "$0: error: can not define $ngx_type" exit 1 fi if [ $ngx_found != yes ]; then echo "typedef $ngx_found $ngx_type;" >> $NGX_AUTO_CONFIG_H fi