CcMapData(): +sanity boundary check of mapped memory by unmapped neighbours

diff --git a/src/libcaptive/cc/map.c b/src/libcaptive/cc/map.c
index aabae76..bab439f 100644 (file)
--- a/src/libcaptive/cc/map.c
+++ b/src/libcaptive/cc/map.c
@@ -769,18 +769,24 @@ GPtrArray *read_array;
 
        /* Create 'base_aligned'; referenced as unaligned by 'privbcb'. */
        /* TODO: on-demand loading */
-       /* Although we do zeroed-page mapping here we just reserve the linears
-        * space by it - all the page will be overriden by shmat(2) afterwards anyway.
+       /* Although we do zeroed-page mapping here we just reserve the linear
+        * space by it.
         */
        base_aligned=mmap(
                        NULL,   /* start */
-                       length_mapped_aligned,  /* length */
+                       PAGE_SIZE+length_mapped_aligned+PAGE_SIZE,      /* length; leading and trailing boundary check pages */
                        PROT_READ|PROT_WRITE,   /* prot; read/write must be possible although write is not guaranteed to be flushed yet */
                        MAP_PRIVATE|MAP_ANONYMOUS,      /* flags */
                        -1,     /* fd; ignored due to MAP_ANONYMOUS */
                        0);     /* offset; ignored due to MAP_ANONYMOUS */
        g_assert(base_aligned!=NULL);
 
+       base_aligned+=PAGE_SIZE;
+       errint=munmap(base_aligned-PAGE_SIZE,PAGE_SIZE);        /* unmap leading boundary check page */
+       g_assert(errint==0);
+       errint=munmap(base_aligned+length_mapped_aligned,PAGE_SIZE);    /* unmap trailing boundary check page */
+       g_assert(errint==0);
+
        /* Create 'PublicBcb'; referenced by 'privbcb'. */
        captive_new(PublicBcb);
        PublicBcb->NodeTypeCode=CAPTIVE_PUBLIC_BCB_NODETYPECODE;