diff options
| -rw-r--r-- | malloc/Makefile | 1 | ||||
| -rw-r--r-- | malloc/tst-malloc-alternate-path.c | 72 |
2 files changed, 73 insertions, 0 deletions
diff --git a/malloc/Makefile b/malloc/Makefile index c1a03f3cb0..cc14cf66c9 100644 --- a/malloc/Makefile +++ b/malloc/Makefile @@ -34,6 +34,7 @@ tests := \ tst-interpose-nothread \ tst-interpose-thread \ tst-malloc \ + tst-malloc-alternate-path \ tst-malloc-backtrace \ tst-malloc-check \ tst-malloc-fork-deadlock \ diff --git a/malloc/tst-malloc-alternate-path.c b/malloc/tst-malloc-alternate-path.c new file mode 100644 index 0000000000..43ae916815 --- /dev/null +++ b/malloc/tst-malloc-alternate-path.c @@ -0,0 +1,72 @@ +/* Test that malloc uses mmap when sbrk or brk fails. + Copyright (C) 2024 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +/* This test sets up an obstruction to ensure that brk/sbrk fails to + grow the heap, then verifies that malloc uses mmap for allocations + instead. */ + +#include <unistd.h> +#include <sys/mman.h> +#include <stdlib.h> +#include <libc-pointer-arith.h> +#include <support/check.h> +#include <stddef.h> +#include <stdalign.h> + +#define LARGE_SIZE (10 * (1 << 20)) // 10 MB +static long page_size; + +static int +do_test (void) +{ + /* Get current program break. */ + void *current_brk = sbrk (0); + + page_size = sysconf (_SC_PAGESIZE); + + /* Round up to the next page boundary. */ + void *next_page_boundary = PTR_ALIGN_UP (current_brk, page_size); + + /* Place a mapping using mmap at the next page boundary. */ + void *obstruction_addr + = mmap (next_page_boundary, page_size, PROT_READ, + MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0); + + /* Check if memory obstruction is set up correctly. */ + TEST_VERIFY_EXIT (obstruction_addr == next_page_boundary); + + /* Try to extend the heap beyond the obstruction using sbrk */ + int *ptr = sbrk (page_size); + TEST_VERIFY_EXIT (ptr == (void *) -1); + + /* Attempt multiple small allocations using malloc. */ + for (size_t i = 0; i < page_size / alignof (max_align_t); i++) + { + TEST_VERIFY (malloc (alignof (max_align_t))); + } + + /* Attempt to allocate a large block of memory using malloc. */ + TEST_VERIFY_EXIT (malloc (LARGE_SIZE) != NULL); + + /* Check if malloc changed current program break. */ + TEST_VERIFY_EXIT (current_brk == sbrk (0)); + + return 0; +} + +#include <support/test-driver.c> |