diff options
Diffstat (limited to 'memcheck.c')
| -rw-r--r-- | memcheck.c | 638 |
1 files changed, 638 insertions, 0 deletions
diff --git a/memcheck.c b/memcheck.c new file mode 100644 index 0000000..b119fad --- /dev/null +++ b/memcheck.c @@ -0,0 +1,638 @@ +/* See LICENSE file for copyright and license details. */ +#include "memcheck.h" + +#include <sys/syscall.h> +#include <sys/mman.h> +#include <errno.h> +#include <stdarg.h> +#include <stddef.h> +#include <stdint.h> +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <unistd.h> + +#define UNW_LOCAL_ONLY +#include <libunwind.h> +#include <elfutils/libdwfl.h> + + +enum alloctype { + ALLOCTYPE_REALLOC, + ALLOCTYPE_MMAP +}; + +#ifdef PRINT_BACKTRACES +struct backtrace { + size_t alloc_size; + size_t n; + uintptr_t rips[]; +}; +#endif + +struct allocinfo { + void *real; + void *ptr; + size_t real_size; + enum alloctype type; + int flags; + int dont_track; +#ifdef PRINT_BACKTRACES + struct backtrace *backtrace; +#endif +}; + + +static struct allocinfo *allocs = NULL; +static size_t nallocs = 0; +static size_t allocs_size = 0; +static size_t alloc_fail_exclusion = 0; +static size_t memleak_exclusion = 1; +static size_t alloc_fail_in = 0; +static int alloc_fail_all = 0; +static int have_custom_malloc = 0; + + +static void * +memcheck_mmap(void *addr, size_t len, int prot, int flags, int fd, off_t off) +{ +#ifdef SYS_mmap2 + unsigned long pgoff = (unsigned long)(off / 4096); + long int r = syscall(SYS_mmap2, addr, len, (unsigned long)prot, (unsigned long)flags, fd, pgoff); +#else + long int r = syscall(SYS_mmap, addr, len, (unsigned long)prot, (unsigned long)flags, fd, off); +#endif + return (void *)r; +} + + +static void * +memcheck_mremap(void *old, size_t old_size, size_t new_size, int flags, void *new_address) +{ + long int r = syscall(SYS_mremap, old, old_size, new_size, flags, new_address); + return (void *)r; +} + + +static int +memcheck_munmap(void *ptr, size_t n) +{ + return (int)syscall(SYS_munmap, ptr, n); +} + + +static void * +memcheck_mmap_ram(size_t n) +{ + return memcheck_mmap(NULL, n, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); +} + + +#ifdef PRINT_BACKTRACES +static struct backtrace * +memcheck_create_backtrace(void) +{ + struct backtrace *ret = NULL, *new; + unw_word_t rip; + unw_cursor_t cursor; + unw_context_t context; + size_t n = 0, size = 0; + int saved_errno = errno; + + memleak_exclusion += 1; + + if (unw_getcontext(&context)) + goto fail; + if (unw_init_local(&cursor, &context)) + goto fail; + + n = 8; + size = offsetof(struct backtrace, rips) + n * sizeof(*ret->rips); + ret = memcheck_mmap_ram(size); + if (!ret) + goto fail; + ret->alloc_size = size; + + ret->n = 0; + while (unw_step(&cursor) > 0) { + if (unw_get_reg(&cursor, UNW_REG_IP, &rip)) + goto fail; + if (ret->n == n) { + n += 8; + size = offsetof(struct backtrace, rips) + n * sizeof(*ret->rips); + new = memcheck_mmap_ram(size); + if (!new) + goto fail; + new->alloc_size = size; + new->n = ret->n; + memcpy(new->rips, ret->rips, n * sizeof(*ret->rips)); + memcheck_munmap(ret, ret->alloc_size); + ret = new; + } + ret->rips[ret->n++] = (uintptr_t)rip; + } + + errno = saved_errno; + memleak_exclusion -= 1; + return ret; + +fail: + if (ret) + memcheck_munmap(ret, ret->alloc_size); + errno = saved_errno; + memleak_exclusion -= 1; + return NULL; +} +#endif + + +#ifdef PRINT_BACKTRACES +static void +memcheck_print_backtrace(struct backtrace *backtrace, const char *indent) +{ + int saved_errno = errno, lineno; + char *debuginfo_path = NULL; + Dwarf_Addr ip; + Dwfl_Callbacks callbacks; + Dwfl *dwfl = NULL; + Dwfl_Line *line = NULL; + Dwfl_Module *module = NULL; + const char *filename = NULL; + const char *funcname = NULL; + size_t i; + + if (!backtrace) + return; + + memleak_exclusion += 1; + + memset(&callbacks, 0, sizeof(callbacks)); + + callbacks.find_elf = dwfl_linux_proc_find_elf; + callbacks.find_debuginfo = dwfl_standard_find_debuginfo; + callbacks.debuginfo_path = &debuginfo_path; + + if (dwfl) { + if (dwfl_linux_proc_report(dwfl, getpid()) || + dwfl_report_end(dwfl, NULL, NULL)) { + perror(""); + dwfl_end(dwfl); + dwfl = NULL; + } + } + + for (i = 0; i < backtrace->n; i++) { + ip = (Dwarf_Addr)backtrace->rips[i]; + + if (dwfl) { + module = dwfl_addrmodule(dwfl, ip); + funcname = module ? dwfl_module_addrname(module, ip) : NULL; + line = dwfl_getsrc(dwfl, ip); + if (line) + filename = dwfl_lineinfo(line, &(Dwarf_Addr){0}, &lineno, NULL, NULL, NULL); + } + + dprintf(STDERR_FILENO, "%s%s 0x%016"PRIxPTR": %s", + indent, !i ? "at" : "by", + (uintptr_t)ip, + funcname ? funcname : "???"); + if (line) + dprintf(STDERR_FILENO, " (%s:%i)\n", filename, lineno); + else + dprintf(STDERR_FILENO, "\n"); + } + + if (dwfl) + dwfl_end(dwfl); + + errno = saved_errno; + memleak_exclusion -= 1; +} +#endif + + +#if defined(__GNUC__) +__attribute__((__format__(__gnu_printf__, 1, 2))) +#endif +static void +memcheck_errorf(const char *fmt, ...) +{ + va_list ap; + memleak_exclusion = 1; + va_start(ap, fmt); + vdprintf(STDERR_FILENO, fmt, ap); + dprintf(STDERR_FILENO, ", aborting...\n"); + va_end(ap); +#ifdef PRINT_BACKTRACES + memcheck_print_backtrace(memcheck_create_backtrace(), "\t"); +#endif + abort(); +} + + +#if defined(__GNUC__) +__attribute__((__pure__)) +#endif +static struct allocinfo * +memcheck_getalloc(void *ptr) +{ + size_t i; + for (i = 0; i < nallocs; i++) + if (allocs[i].ptr == ptr) + return &allocs[i]; + return NULL; +} + + +static int +memcheck_fake_fail(void) +{ + have_custom_malloc = 1; + + if (!alloc_fail_exclusion) { + if (alloc_fail_all || (alloc_fail_in && !--alloc_fail_in)) { + alloc_fail_all = 1; + errno = ENOMEM; + return 1; + } + } + + return 0; +} + + +static void +memcheck_putalloc(struct allocinfo *info) +{ + if (nallocs == allocs_size) { + size_t old_allocs_size = allocs_size; + void *new; + if (allocs_size > SIZE_MAX / sizeof(*allocs) - 64) + memcheck_errorf("size of memory bookkeeping will exceed SIZE_MAX"); + allocs_size += 64; + new = memcheck_mmap_ram(allocs_size * sizeof(*allocs)); + if (!new) + memcheck_errorf("failed to allocate enought memory for bookkeeping"); + if (allocs) { + memcpy(new, allocs, nallocs * sizeof(*allocs)); + memcheck_munmap(allocs, old_allocs_size * sizeof(*allocs)); + } + allocs = new; + } + allocs[nallocs++] = *info; +} + + +static int +memcheck_free(void *ptr, size_t size, enum alloctype type) +{ + int ret; + struct allocinfo *alloc; + alloc = memcheck_getalloc(ptr); + if (!alloc) + memcheck_errorf("attempting to deallocate unknown pointer %p", ptr); + if (alloc->type != type) + memcheck_errorf("attempting to deallocating with incompatible function"); + if (type == ALLOCTYPE_MMAP && size != alloc->real_size) + memcheck_errorf("attempting to munmap(2) pointer %p with wrong size", ptr); + ret = memcheck_munmap(alloc->real, alloc->real_size); +#ifdef PRINT_BACKTRACES + if (alloc->backtrace) + memcheck_munmap(alloc->backtrace, alloc->backtrace->alloc_size); +#endif + *alloc = allocs[--nallocs]; + if (!nallocs) { + memcheck_munmap(allocs, allocs_size * sizeof(*allocs)); + allocs = NULL; + nallocs = 0; + allocs_size = 0; + } + return ret; +} + + +static void * +memcheck_realloc(void *old, size_t n, size_t m, size_t alignment, int initbyte) +{ + struct allocinfo info; + uintptr_t addr; + void *ret; + + if (memcheck_fake_fail()) + return NULL; + + if (!n || !m) + memcheck_errorf("attempting to allocate with zero size which is implementation-defined behaviour"); + if (n > SIZE_MAX / m) + memcheck_errorf("attempting allocate more than SIZE_MAX"); + + if (!alignment) + alignment = _Alignof(max_align_t); + + n *= m; + if (n > SIZE_MAX - (alignment - 1U)) + memcheck_errorf("attempting allocate more than SIZE_MAX after alignment padding"); + +#ifdef PRINT_BACKTRACES + info.backtrace = memleak_exclusion ? NULL : memcheck_create_backtrace(); +#endif + info.dont_track = memleak_exclusion > 0; + info.flags = 0; + info.type = ALLOCTYPE_REALLOC; + info.real_size = n + (alignment - 1U); + info.real = memcheck_mmap_ram(info.real_size); + if (!info.real) + memcheck_errorf("failed to allocate enough memory"); + memset(info.real, initbyte, info.real_size); + + addr = (uintptr_t)info.real; + if (addr % alignment) + addr += alignment - addr % alignment; + ret = info.ptr = (void *)addr; + + memcheck_putalloc(&info); + + if (old) { + struct allocinfo *oldinfo; + oldinfo = memcheck_getalloc(old); + if (!oldinfo) + memcheck_errorf("attempting to reallocate unknown pointer %p", old); + memcpy(info.real, oldinfo->real, info.real_size < oldinfo->real_size ? info.real_size : oldinfo->real_size); + memcheck_free(old, 0, ALLOCTYPE_REALLOC); + } + + return ret; +} + + + +/* Implementation of checked functions */ + + +#if defined(__GNUC__) +# pragma GCC diagnostic push +# pragma GCC diagnostic ignored "-Wmissing-prototypes" +#endif + + +void * +mmap(void *addr, size_t len, int prot, int flags, int fd, off_t off) +{ + struct allocinfo info; + void *ret; + + if (off % 4096) + memcheck_errorf("attempting to mmap(2) with offset %ju which is not a multiple of 4096", (uintmax_t)off); + +#ifdef PRINT_BACKTRACES + info.backtrace = memleak_exclusion ? NULL : memcheck_create_backtrace(); +#endif + info.dont_track = memleak_exclusion > 0; + info.flags = flags; + info.type = ALLOCTYPE_MMAP; + info.real_size = len; + info.real = memcheck_mmap(addr, len, prot, flags, fd, off); + if (!info.real) + memcheck_errorf("failed to mmap(2)"); + ret = info.ptr = info.real; + + memcheck_putalloc(&info); + return ret; +} + + +int +munmap(void *ptr, size_t n) +{ + return memcheck_free(ptr, n, ALLOCTYPE_MMAP); +} + + +void * +mremap(void *old, size_t old_size, size_t new_size, int flags, ...) +{ + struct allocinfo *oldinfo; + void *new_address = NULL; + void *ret; + + if (memcheck_fake_fail()) + return NULL; + + oldinfo = memcheck_getalloc(old); + if (!oldinfo) + memcheck_errorf("attempting to mremap(2) unknown pointer %p", old); + if (oldinfo->type != ALLOCTYPE_MMAP) + memcheck_errorf("attempting to mremap(2) pointer %p that was not allocated with mmap(2) or mremap(2)", old); + + if (flags & MREMAP_FIXED) { + va_list ap; + va_start(ap, flags); + new_address = va_arg(ap, void *); + va_end(ap); + } + + ret = memcheck_mremap(old, old_size, new_size, flags, new_address); + if (!ret) + return NULL; + + if (ret == old || !(flags & MREMAP_DONTUNMAP)) { + oldinfo->ptr = oldinfo->real = ret; + oldinfo->real_size = new_size; + } else { + struct allocinfo info; + info = *oldinfo; + info.ptr = info.real = ret; + info.real_size = new_size; + memcheck_putalloc(&info); + } + + return ret; +} + + +void +free(void *ptr) +{ + if (!ptr) + return; + memcheck_free(ptr, 0, ALLOCTYPE_REALLOC); +} + + +void * +malloc(size_t n) +{ + return memcheck_realloc(NULL, 1, n, 0, 'x'); +} + + +void * +calloc(size_t n, size_t m) +{ + return memcheck_realloc(NULL, n, m, 0, 0); +} + + +void * +realloc(void *old, size_t n) +{ + return memcheck_realloc(old, 1, n, 0, 'x'); +} + + +void * +reallocarray(void *old, size_t n, size_t m) +{ + return memcheck_realloc(old, n, m, 0, 'x'); +} + + +void * +memdup(const void *s, size_t n) +{ + char *r = memcheck_realloc(NULL, 1, n, 0, 'x'); + if (r) + memcpy(r, s, n); + return r; +} + + +char * +strdup(const char *s) +{ + size_t n = strlen(s) + 1U; + char *r = memcheck_realloc(NULL, 1, n, 0, 'x'); + if (r) + memcpy(r, s, n); + return r; +} + + +char * +strndup(const char *s, size_t max) +{ + size_t n = strnlen(s, max) + 1U; + char *r = memcheck_realloc(NULL, 1, n, 0, 'x'); + if (n > max) + n = max; + if (r) + memcpy(r, s, n); + return r; +} + + +int +posix_memalign(void **ret_out, size_t align, size_t n) +{ + int saved_errno, r; + saved_errno = errno, errno = 0; + if (!align || (align & (align - 1U)) || align % sizeof(void *)) + memcheck_errorf("invalid alignment for posix_memalign: %zu", align); + *ret_out = memcheck_realloc(NULL, 1, n, align, 'x'); + return r = errno, errno = saved_errno, r; +} + + +void * +memalign(size_t align, size_t n) +{ + if (!align) + memcheck_errorf("invalid alignment for memalign: %zu", align); + return memcheck_realloc(NULL, 1, n, align, 'x'); +} + + +void * +aligned_alloc(size_t align, size_t n) +{ + if (!align || (align & (align - 1U))) + memcheck_errorf("invalid alignment for aligned_alloc: %zu", align); + return memcheck_realloc(NULL, 1, n, align, 'x'); +} + + +void * +valloc(size_t n) +{ + return memcheck_realloc(NULL, 1, n, 4096U, 'x'); +} + + +void * +pvalloc(size_t n) +{ + if (n % 4096U) { + n |= 4096U - 1U; + if (n == SIZE_MAX) + memcheck_errorf("attempting to allocate beyond SIZE_MAX"); + n += 1U; + } + return memcheck_realloc(NULL, 1, n, 4096U, 'x'); +} + + +#if defined(__GNUC__) +# pragma GCC diagnostic pop +#endif + + + +/* Test functions */ + + +int +memcheck_have_custom_malloc(void) +{ + static void *volatile test_have_custom_malloc_ptr = NULL; + int saved_errno = errno; + alloc_fail_exclusion++; + memleak_exclusion++; + test_have_custom_malloc_ptr = malloc(1); + free(test_have_custom_malloc_ptr); + memleak_exclusion--; + alloc_fail_exclusion--; + errno = saved_errno; + return have_custom_malloc; +} + +size_t +memcheck_alloc_fail_in(size_t n) +{ + size_t ret = alloc_fail_in; + alloc_fail_in = n; + alloc_fail_all = 0; + return ret; +} + + +int +memcheck_check_memleaks(void) +{ + struct allocinfo *leak; + size_t i, count = 0; + memleak_exclusion = 1; + for (i = 0; i < nallocs; i++) { + leak = &allocs[i]; + if (leak->dont_track) + continue; + count += 1; + } + if (!count) + return 1; + dprintf(STDERR_FILENO, "%zu %s!\n", count, count == 1 ? "memory leak" : "memory leaks"); +#ifdef PRINT_BACKTRACES + for (i = 0; i < nallocs; i++) { + leak = &allocs[i]; + if (leak->dont_track) + continue; + memcheck_print_backtrace(leak->backtrace, "\t"); + } +#endif + return 0; +} + +void memcheck_alloc_fail_exclusion_begin(void) { alloc_fail_exclusion++; } +void memcheck_alloc_fail_exclusion_end(void) { alloc_fail_exclusion--; } +void memcheck_exclusion_begin(void) { memleak_exclusion++; } +void memcheck_exclusion_end(void) { memleak_exclusion--; } +void memcheck_begin(void) { memleak_exclusion = 0; } |