implement PT_GNU_RELRO support

[musl] / src / malloc / malloc.c

diff --git a/src/malloc/malloc.c b/src/malloc/malloc.c
index 88a31ae..d6ad904 100644 (file)
--- a/src/malloc/malloc.c
+++ b/src/malloc/malloc.c
@@ -64,28 +64,27 @@ static struct {
 
 static inline void lock(volatile int *lk)
 {
-       if (!libc.threads_minus_1) return;
-       while(a_swap(lk, 1)) __wait(lk, lk+1, 1, 1);
+       if (libc.threads_minus_1)
+               while(a_swap(lk, 1)) __wait(lk, lk+1, 1, 1);
 }
 
 static inline void unlock(volatile int *lk)
 {
-       if (!libc.threads_minus_1) return;
-       a_store(lk, 0);
-       if (lk[1]) __wake(lk, 1, 1);
+       if (lk[0]) {
+               a_store(lk, 0);
+               if (lk[1]) __wake(lk, 1, 1);
+       }
 }
 
 static inline void lock_bin(int i)
 {
-       if (libc.threads_minus_1)
-               lock(mal.bins[i].lock);
+       lock(mal.bins[i].lock);
        if (!mal.bins[i].head)
                mal.bins[i].head = mal.bins[i].tail = BIN_TO_CHUNK(i);
 }
 
 static inline void unlock_bin(int i)
 {
-       if (!libc.threads_minus_1) return;
        unlock(mal.bins[i].lock);
 }
 
@@ -178,6 +177,7 @@ static struct chunk *expand_heap(size_t n)
        return w;
 fail:
        unlock(mal.brk_lock);
+       errno = ENOMEM;
        return 0;
 }
 
@@ -196,7 +196,11 @@ static int init_malloc(size_t n)
                return 0;
        }
 
-       mal.brk = __brk(0) + 2*SIZE_ALIGN-1 & -SIZE_ALIGN;
+       mal.brk = __brk(0);
+#ifdef SHARED
+       mal.brk = mal.brk + PAGE_SIZE-1 & -PAGE_SIZE;
+#endif
+       mal.brk = mal.brk + 2*SIZE_ALIGN-1 & -SIZE_ALIGN;
 
        c = expand_heap(n);
 
@@ -414,6 +418,9 @@ void *realloc(void *p, size_t n)
 
        next = NEXT_CHUNK(self);
 
+       /* Crash on corrupted footer (likely from buffer overflow) */
+       if (next->psize != self->csize) a_crash();
+
        /* Merge adjacent chunks if we need more space. This is not
         * a waste of time even if we fail to get enough space, because our
         * subsequent call to free would otherwise have to do the merge. */
@@ -467,6 +474,9 @@ void free(void *p)
        final_size = new_size = CHUNK_SIZE(self);
        next = NEXT_CHUNK(self);
 
+       /* Crash on corrupted footer (likely from buffer overflow) */
+       if (next->psize != self->csize) a_crash();
+
        for (;;) {
                /* Replace middle of large chunks with fresh zero pages */
                if (reclaim && (self->psize & next->csize & C_INUSE)) {