Fix mprotect to it hands back the correct end address

diff --git a/src/lib/util/talloc.c b/src/lib/util/talloc.c
index cb9e9429f58e341d3fad4180fb61265d6ea43d5d..ae749e2a03ac1f7e2769f7ee586b1b1a8341669c 100644 (file)
--- a/src/lib/util/talloc.c
+++ b/src/lib/util/talloc.c
@@ -311,7 +311,7 @@ ssize_t talloc_hdr_size(void)
  */
 TALLOC_CTX *talloc_page_aligned_pool(TALLOC_CTX *ctx, void **start, size_t *end_len, unsigned int headers, size_t size)
 {
-       size_t          rounded, page_size = (size_t)getpagesize();
+       size_t          rounded, alloced, page_size = (size_t)getpagesize();
        size_t          hdr_size;
        void            *next;
        TALLOC_CTX      *pool;
@@ -339,9 +339,8 @@ TALLOC_CTX *talloc_page_aligned_pool(TALLOC_CTX *ctx, void **start, size_t *end_
         *  will give to talloc, and what the first address after adding the
         *  pools header will be
         */
-       rounded += page_size;
-
-       pool = talloc_pool(ctx, rounded);
+       alloced = rounded + page_size;
+       pool = talloc_pool(ctx, alloced);
        if (!pool) {
                fr_strerror_const("Out of memory");
                return NULL;
@@ -382,6 +381,28 @@ TALLOC_CTX *talloc_page_aligned_pool(TALLOC_CTX *ctx, void **start, size_t *end_
        *start = next;                  /* This is the address we feed into mprotect */
        *end_len = rounded;             /* This is how much memory we protect */
 
+       /*
+        *      Start address must be page aligned
+        */
+       fr_assert(((uintptr_t)*start % page_size) == 0);
+
+       /*
+        *      For our sanity, length must be a multiple of the page size.
+        *      mprotect will silently protect an entire additional page
+        *      if length is not a multiple of page size.
+        */
+       fr_assert(((uintptr_t)*end_len % page_size) == 0);
+
+       /*
+        *      We can't protect pages before the pool
+        */
+       fr_assert(*start >= pool);
+
+       /*
+        *      We can't protect pages after the pool
+        */
+       fr_assert(((uintptr_t)*start + *end_len) < ((uintptr_t)pool + alloced));
+
        return pool;
 }