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Core: fixed ngx_pcre_studies cleanup.

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If a configuration parsing fails for some reason, ngx_regex_module_init()
is not called, and ngx_pcre_studies remained set despite the fact that
the pool it was allocated from is already freed.  This might result in
a segmentation fault during runtime regular expression compilation, such
as in SSI, for example, in the single process mode, or if a worker process
died and was respawned from a master process in such an inconsistent state.

Fix is to clear ngx_pcre_studies from the pool cleanup handler (which is
anyway used to free JIT-compiled patterns).
This commit is contained in:
Maxim Dounin 2021-12-25 01:07:10 +03:00
parent 363505e806
commit 09268f58b4
1 changed files with 52 additions and 49 deletions
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101
src/core/ngx_regex.c
View File

@ -10,15 +10,14 @@
typedef struct {
ngx_flag_t pcre_jit;
ngx_flag_t pcre_jit;
ngx_list_t *studies;
} ngx_regex_conf_t;
static void * ngx_libc_cdecl ngx_regex_malloc(size_t size);
static void ngx_libc_cdecl ngx_regex_free(void *p);
#if (NGX_HAVE_PCRE_JIT)
static void ngx_pcre_free_studies(void *data);
#endif
static void ngx_regex_cleanup(void *data);
static ngx_int_t ngx_regex_module_init(ngx_cycle_t *cycle);
@ -248,18 +247,17 @@ ngx_regex_free(void *p)
}
#if (NGX_HAVE_PCRE_JIT)
static void
ngx_pcre_free_studies(void *data)
ngx_regex_cleanup(void *data)
{
ngx_list_t *studies = data;
#if (NGX_HAVE_PCRE_JIT)
ngx_regex_conf_t *rcf = data;
ngx_uint_t i;
ngx_list_part_t *part;
ngx_regex_elt_t *elts;
part = &studies->part;
part = &rcf->studies->part;
elts = part->elts;
for (i = 0; /* void */ ; i++) {
@ -274,56 +272,50 @@ ngx_pcre_free_studies(void *data)
i = 0;
}
if (elts[i].regex->extra != NULL) {
pcre_free_study(elts[i].regex->extra);
}
}
}
#endif
static ngx_int_t
ngx_regex_module_init(ngx_cycle_t *cycle)
{
int opt;
const char *errstr;
ngx_uint_t i;
ngx_list_part_t *part;
ngx_regex_elt_t *elts;
opt = 0;
#if (NGX_HAVE_PCRE_JIT)
{
ngx_regex_conf_t *rcf;
ngx_pool_cleanup_t *cln;
rcf = (ngx_regex_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_regex_module);
if (rcf->pcre_jit) {
opt = PCRE_STUDY_JIT_COMPILE;
/*
* The PCRE JIT compiler uses mmap for its executable codes, so we
* have to explicitly call the pcre_free_study() function to free
* this memory.
*/
cln = ngx_pool_cleanup_add(cycle->pool, 0);
if (cln == NULL) {
return NGX_ERROR;
if (elts[i].regex->extra != NULL) {
pcre_free_study(elts[i].regex->extra);
}
cln->handler = ngx_pcre_free_studies;
cln->data = ngx_pcre_studies;
}
#endif
/*
* On configuration parsing errors ngx_regex_module_init() will not
* be called. Make sure ngx_pcre_studies is properly cleared anyway.
*/
ngx_pcre_studies = NULL;
}
static ngx_int_t
ngx_regex_module_init(ngx_cycle_t *cycle)
{
int opt;
const char *errstr;
ngx_uint_t i;
ngx_list_part_t *part;
ngx_regex_elt_t *elts;
ngx_regex_conf_t *rcf;
opt = 0;
rcf = (ngx_regex_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_regex_module);
#if (NGX_HAVE_PCRE_JIT)
if (rcf->pcre_jit) {
opt = PCRE_STUDY_JIT_COMPILE;
}
#endif
ngx_regex_malloc_init(cycle->pool);
part = &ngx_pcre_studies->part;
part = &rcf->studies->part;
elts = part->elts;
for (i = 0; /* void */ ; i++) {
@ -374,7 +366,8 @@ ngx_regex_module_init(ngx_cycle_t *cycle)
static void *
ngx_regex_create_conf(ngx_cycle_t *cycle)
{
ngx_regex_conf_t *rcf;
ngx_regex_conf_t *rcf;
ngx_pool_cleanup_t *cln;
rcf = ngx_pcalloc(cycle->pool, sizeof(ngx_regex_conf_t));
if (rcf == NULL) {
@ -383,11 +376,21 @@ ngx_regex_create_conf(ngx_cycle_t *cycle)
rcf->pcre_jit = NGX_CONF_UNSET;
ngx_pcre_studies = ngx_list_create(cycle->pool, 8, sizeof(ngx_regex_elt_t));
if (ngx_pcre_studies == NULL) {
cln = ngx_pool_cleanup_add(cycle->pool, 0);
if (cln == NULL) {
return NULL;
}
cln->handler = ngx_regex_cleanup;
cln->data = rcf;
rcf->studies = ngx_list_create(cycle->pool, 8, sizeof(ngx_regex_elt_t));
if (rcf->studies == NULL) {
return NULL;
}
ngx_pcre_studies = rcf->studies;
return rcf;
}