https://github.com/google/kmsan
Revision e6bc8833d80fb695515a8144aa1dc13468db9d4d authored by Alexander Potapenko on 27 February 2023, 15:44:58 UTC, committed by Alexander Potapenko on 19 June 2023, 08:56:03 UTC
lib/string.c is built with -ffreestanding, which prevents the compiler from replacing certain functions with calls to their library versions. On the other hand, this also prevents Clang and GCC from instrumenting calls to memcpy() when building with KASAN, KCSAN or KMSAN: - KASAN normally replaces memcpy() with __asan_memcpy() with the additional cc-param,asan-kernel-mem-intrinsic-prefix=1; - KCSAN and KMSAN replace memcpy() with __tsan_memcpy() and __msan_memcpy() by default. To let the tools catch memory accesses from strlcpy/strlcat, replace the calls to memcpy() with __builtin_memcpy(), which KASAN, KCSAN and KMSAN are able to replace even in -ffreestanding mode. This preserves the behavior in normal builds (__builtin_memcpy() ends up being replaced with memcpy()), and does not introduce new instrumentation in unwanted places, as strlcpy/strlcat are already instrumented. Suggested-by: Marco Elver <elver@google.com> Signed-off-by: Alexander Potapenko <glider@google.com> Link: https://lore.kernel.org/all/20230224085942.1791837-1-elver@google.com/ Acked-by: Kees Cook <keescook@chromium.org>
1 parent 11aac78
Tip revision: e6bc8833d80fb695515a8144aa1dc13468db9d4d authored by Alexander Potapenko on 27 February 2023, 15:44:58 UTC
string: use __builtin_memcpy() in strlcpy/strlcat
string: use __builtin_memcpy() in strlcpy/strlcat
Tip revision: e6bc883
fadvise.c
// SPDX-License-Identifier: GPL-2.0
/*
* mm/fadvise.c
*
* Copyright (C) 2002, Linus Torvalds
*
* 11Jan2003 Andrew Morton
* Initial version.
*/
#include <linux/kernel.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/backing-dev.h>
#include <linux/pagevec.h>
#include <linux/fadvise.h>
#include <linux/writeback.h>
#include <linux/syscalls.h>
#include <linux/swap.h>
#include <asm/unistd.h>
#include "internal.h"
/*
* POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
* deactivate the pages and clear PG_Referenced.
*/
int generic_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
{
struct inode *inode;
struct address_space *mapping;
struct backing_dev_info *bdi;
loff_t endbyte; /* inclusive */
pgoff_t start_index;
pgoff_t end_index;
unsigned long nrpages;
inode = file_inode(file);
if (S_ISFIFO(inode->i_mode))
return -ESPIPE;
mapping = file->f_mapping;
if (!mapping || len < 0)
return -EINVAL;
bdi = inode_to_bdi(mapping->host);
if (IS_DAX(inode) || (bdi == &noop_backing_dev_info)) {
switch (advice) {
case POSIX_FADV_NORMAL:
case POSIX_FADV_RANDOM:
case POSIX_FADV_SEQUENTIAL:
case POSIX_FADV_WILLNEED:
case POSIX_FADV_NOREUSE:
case POSIX_FADV_DONTNEED:
/* no bad return value, but ignore advice */
break;
default:
return -EINVAL;
}
return 0;
}
/*
* Careful about overflows. Len == 0 means "as much as possible". Use
* unsigned math because signed overflows are undefined and UBSan
* complains.
*/
endbyte = (u64)offset + (u64)len;
if (!len || endbyte < len)
endbyte = LLONG_MAX;
else
endbyte--; /* inclusive */
switch (advice) {
case POSIX_FADV_NORMAL:
file->f_ra.ra_pages = bdi->ra_pages;
spin_lock(&file->f_lock);
file->f_mode &= ~(FMODE_RANDOM | FMODE_NOREUSE);
spin_unlock(&file->f_lock);
break;
case POSIX_FADV_RANDOM:
spin_lock(&file->f_lock);
file->f_mode |= FMODE_RANDOM;
spin_unlock(&file->f_lock);
break;
case POSIX_FADV_SEQUENTIAL:
file->f_ra.ra_pages = bdi->ra_pages * 2;
spin_lock(&file->f_lock);
file->f_mode &= ~FMODE_RANDOM;
spin_unlock(&file->f_lock);
break;
case POSIX_FADV_WILLNEED:
/* First and last PARTIAL page! */
start_index = offset >> PAGE_SHIFT;
end_index = endbyte >> PAGE_SHIFT;
/* Careful about overflow on the "+1" */
nrpages = end_index - start_index + 1;
if (!nrpages)
nrpages = ~0UL;
force_page_cache_readahead(mapping, file, start_index, nrpages);
break;
case POSIX_FADV_NOREUSE:
spin_lock(&file->f_lock);
file->f_mode |= FMODE_NOREUSE;
spin_unlock(&file->f_lock);
break;
case POSIX_FADV_DONTNEED:
__filemap_fdatawrite_range(mapping, offset, endbyte,
WB_SYNC_NONE);
/*
* First and last FULL page! Partial pages are deliberately
* preserved on the expectation that it is better to preserve
* needed memory than to discard unneeded memory.
*/
start_index = (offset+(PAGE_SIZE-1)) >> PAGE_SHIFT;
end_index = (endbyte >> PAGE_SHIFT);
/*
* The page at end_index will be inclusively discarded according
* by invalidate_mapping_pages(), so subtracting 1 from
* end_index means we will skip the last page. But if endbyte
* is page aligned or is at the end of file, we should not skip
* that page - discarding the last page is safe enough.
*/
if ((endbyte & ~PAGE_MASK) != ~PAGE_MASK &&
endbyte != inode->i_size - 1) {
/* First page is tricky as 0 - 1 = -1, but pgoff_t
* is unsigned, so the end_index >= start_index
* check below would be true and we'll discard the whole
* file cache which is not what was asked.
*/
if (end_index == 0)
break;
end_index--;
}
if (end_index >= start_index) {
unsigned long nr_pagevec = 0;
/*
* It's common to FADV_DONTNEED right after
* the read or write that instantiates the
* pages, in which case there will be some
* sitting on the local LRU cache. Try to
* avoid the expensive remote drain and the
* second cache tree walk below by flushing
* them out right away.
*/
lru_add_drain();
invalidate_mapping_pagevec(mapping,
start_index, end_index,
&nr_pagevec);
/*
* If fewer pages were invalidated than expected then
* it is possible that some of the pages were on
* a per-cpu pagevec for a remote CPU. Drain all
* pagevecs and try again.
*/
if (nr_pagevec) {
lru_add_drain_all();
invalidate_mapping_pages(mapping, start_index,
end_index);
}
}
break;
default:
return -EINVAL;
}
return 0;
}
EXPORT_SYMBOL(generic_fadvise);
int vfs_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
{
if (file->f_op->fadvise)
return file->f_op->fadvise(file, offset, len, advice);
return generic_fadvise(file, offset, len, advice);
}
EXPORT_SYMBOL(vfs_fadvise);
#ifdef CONFIG_ADVISE_SYSCALLS
int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
{
struct fd f = fdget(fd);
int ret;
if (!f.file)
return -EBADF;
ret = vfs_fadvise(f.file, offset, len, advice);
fdput(f);
return ret;
}
SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
{
return ksys_fadvise64_64(fd, offset, len, advice);
}
#ifdef __ARCH_WANT_SYS_FADVISE64
SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
{
return ksys_fadvise64_64(fd, offset, len, advice);
}
#endif
#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FADVISE64_64)
COMPAT_SYSCALL_DEFINE6(fadvise64_64, int, fd, compat_arg_u64_dual(offset),
compat_arg_u64_dual(len), int, advice)
{
return ksys_fadvise64_64(fd, compat_arg_u64_glue(offset),
compat_arg_u64_glue(len), advice);
}
#endif
#endif
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