fixed a bug in slab_defrag.patch for the nginx core that we may incorrectly access the padding area between the end of pool->pages and pool->start. thanks Shuxin Yang for the catch.

This commit is contained in:
Yichun Zhang (agentzh) 2014-05-07 13:10:59 -07:00
parent 05334f1b5b
commit 20e69718ce
1 changed files with 27 additions and 10 deletions

View File

@ -1,7 +1,15 @@
diff -r 48c97d83ab7f src/core/ngx_slab.c
--- a/src/core/ngx_slab.c Tue Apr 29 22:22:38 2014 +0200
+++ b/src/core/ngx_slab.c Tue May 06 16:22:20 2014 -0700
@@ -118,6 +118,7 @@
+++ b/src/core/ngx_slab.c Wed May 07 13:01:57 2014 -0700
@@ -111,6 +111,7 @@
ngx_memzero(p, pages * sizeof(ngx_slab_page_t));
pool->pages = (ngx_slab_page_t *) p;
+ pool->npages = pages;
pool->free.prev = 0;
pool->free.next = (ngx_slab_page_t *) p;
@@ -118,6 +119,7 @@
pool->pages->slab = pages;
pool->pages->next = &pool->free;
pool->pages->prev = (uintptr_t) &pool->free;
@ -9,7 +17,7 @@ diff -r 48c97d83ab7f src/core/ngx_slab.c
pool->start = (u_char *)
ngx_align_ptr((uintptr_t) p + pages * sizeof(ngx_slab_page_t),
@@ -629,6 +630,7 @@
@@ -629,6 +631,7 @@
page[pages].slab = page->slab - pages;
page[pages].next = page->next;
page[pages].prev = page->prev;
@ -17,7 +25,7 @@ diff -r 48c97d83ab7f src/core/ngx_slab.c
p = (ngx_slab_page_t *) page->prev;
p->next = &page[pages];
@@ -652,6 +654,7 @@
@@ -652,6 +655,7 @@
p->slab = NGX_SLAB_PAGE_BUSY;
p->next = NULL;
p->prev = NGX_SLAB_PAGE;
@ -25,7 +33,7 @@ diff -r 48c97d83ab7f src/core/ngx_slab.c
p++;
}
@@ -672,7 +675,7 @@
@@ -672,7 +676,7 @@
ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page,
ngx_uint_t pages)
{
@ -34,14 +42,14 @@ diff -r 48c97d83ab7f src/core/ngx_slab.c
page->slab = pages--;
@@ -686,6 +689,51 @@
@@ -686,6 +690,51 @@
page->next->prev = page->prev;
}
+ /* merge the next adjacent free block if it is free */
+
+ p = &page[page->slab];
+ if ((u_char *) p < pool->start
+ if (p < pool->pages + pool->npages
+ && !(p->slab & NGX_SLAB_PAGE_START)
+ && p->next != NULL
+ && (p->prev & NGX_SLAB_PAGE_MASK) == NGX_SLAB_PAGE)
@ -57,7 +65,7 @@ diff -r 48c97d83ab7f src/core/ngx_slab.c
+ ngx_memzero(p, sizeof(ngx_slab_page_t));
+
+ /* adjust the "prev_slab" field in the next next adjacent block */
+ if ((u_char *) (p + p->slab) < pool->start) {
+ if (p + p->slab < pool->pages + pool->npages) {
+ p[p->slab].prev_slab = page->slab;
+ }
+ }
@ -74,7 +82,7 @@ diff -r 48c97d83ab7f src/core/ngx_slab.c
+ ngx_memzero(page, sizeof(ngx_slab_page_t));
+
+ /* adjust the "prev_slab" field in the next adjacent block */
+ if ((u_char *) (p + p->slab) < pool->start) {
+ if (p + p->slab < pool->pages + pool->npages) {
+ p[p->slab].prev_slab = p->slab;
+ }
+
@ -88,7 +96,7 @@ diff -r 48c97d83ab7f src/core/ngx_slab.c
diff -r 48c97d83ab7f src/core/ngx_slab.h
--- a/src/core/ngx_slab.h Tue Apr 29 22:22:38 2014 +0200
+++ b/src/core/ngx_slab.h Tue May 06 16:22:20 2014 -0700
+++ b/src/core/ngx_slab.h Wed May 07 13:01:57 2014 -0700
@@ -19,6 +19,8 @@
uintptr_t slab;
ngx_slab_page_t *next;
@ -98,3 +106,12 @@ diff -r 48c97d83ab7f src/core/ngx_slab.h
};
@@ -31,6 +33,8 @@
ngx_slab_page_t *pages;
ngx_slab_page_t free;
+ ngx_uint_t npages;
+
u_char *start;
u_char *end;