Merge tag 'for-linus-iommufd' of git://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd

Pull iommufd fixes from Jason Gunthorpe:
 "Some changes to the userspace selftest framework cause the iommufd
  tests to start failing. This turned out to be bugs in the iommufd side
  that were just getting uncovered.

   - Deal with MAP_HUGETLB mmaping more than requested even when in
     MAP_FIXED mode

   - Fixup missing error flow cleanup in the test

   - Check that the memory allocations suceeded

   - Suppress some bogus gcc 'may be used uninitialized' warnings"

* tag 'for-linus-iommufd' of git://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd:
  iommufd/selftest: Fix build warnings due to uninitialized mfd
  iommufd/selftest: Add asserts testing global mfd
  iommufd/selftest: Add missing close(mfd) in memfd_mmap()
  iommufd/selftest: Fix iommufd_dirty_tracking with large hugepage sizes

Author: torvalds

tools/testing/selftests/iommu/iommufd.c

@@ -54,6 +54,8 @@ static __attribute__((constructor)) void setup_sizes(void)
 
 	mfd_buffer = memfd_mmap(BUFFER_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED,
 				&mfd);
+	assert(mfd_buffer != MAP_FAILED);
+	assert(mfd > 0);
 }
 
 FIXTURE(iommufd)
@@ -1746,13 +1748,15 @@ TEST_F(iommufd_mock_domain, all_aligns)
 	unsigned int end;
 	uint8_t *buf;
 	int prot = PROT_READ | PROT_WRITE;
-	int mfd;
+	int mfd = -1;
 
 	if (variant->file)
 		buf = memfd_mmap(buf_size, prot, MAP_SHARED, &mfd);
 	else
 		buf = mmap(0, buf_size, prot, self->mmap_flags, -1, 0);
 	ASSERT_NE(MAP_FAILED, buf);
+	if (variant->file)
+		ASSERT_GT(mfd, 0);
 	check_refs(buf, buf_size, 0);
 
 	/*
@@ -1798,13 +1802,15 @@ TEST_F(iommufd_mock_domain, all_aligns_copy)
 	unsigned int end;
 	uint8_t *buf;
 	int prot = PROT_READ | PROT_WRITE;
-	int mfd;
+	int mfd = -1;
 
 	if (variant->file)
 		buf = memfd_mmap(buf_size, prot, MAP_SHARED, &mfd);
 	else
 		buf = mmap(0, buf_size, prot, self->mmap_flags, -1, 0);
 	ASSERT_NE(MAP_FAILED, buf);
+	if (variant->file)
+		ASSERT_GT(mfd, 0);
 	check_refs(buf, buf_size, 0);
 
 	/*
@@ -2008,6 +2014,7 @@ FIXTURE_VARIANT(iommufd_dirty_tracking)
 
 FIXTURE_SETUP(iommufd_dirty_tracking)
 {
+	size_t mmap_buffer_size;
 	unsigned long size;
 	int mmap_flags;
 	void *vrc;
@@ -2022,22 +2029,33 @@ FIXTURE_SETUP(iommufd_dirty_tracking)
 	self->fd = open("/dev/iommu", O_RDWR);
 	ASSERT_NE(-1, self->fd);
 
-	rc = posix_memalign(&self->buffer, HUGEPAGE_SIZE, variant->buffer_size);
-	if (rc || !self->buffer) {
-		SKIP(return, "Skipping buffer_size=%lu due to errno=%d",
-			   variant->buffer_size, rc);
-	}
-
 	mmap_flags = MAP_SHARED | MAP_ANONYMOUS | MAP_FIXED;
+	mmap_buffer_size = variant->buffer_size;
 	if (variant->hugepages) {
 		/*
 		 * MAP_POPULATE will cause the kernel to fail mmap if THPs are
 		 * not available.
 		 */
 		mmap_flags |= MAP_HUGETLB | MAP_POPULATE;
+
+		/*
+		 * Allocation must be aligned to the HUGEPAGE_SIZE, because the
+		 * following mmap() will automatically align the length to be a
+		 * multiple of the underlying huge page size. Failing to do the
+		 * same at this allocation will result in a memory overwrite by
+		 * the mmap().
+		 */
+		if (mmap_buffer_size < HUGEPAGE_SIZE)
+			mmap_buffer_size = HUGEPAGE_SIZE;
+	}
+
+	rc = posix_memalign(&self->buffer, HUGEPAGE_SIZE, mmap_buffer_size);
+	if (rc || !self->buffer) {
+		SKIP(return, "Skipping buffer_size=%lu due to errno=%d",
+			   mmap_buffer_size, rc);
 	}
 	assert((uintptr_t)self->buffer % HUGEPAGE_SIZE == 0);
-	vrc = mmap(self->buffer, variant->buffer_size, PROT_READ | PROT_WRITE,
+	vrc = mmap(self->buffer, mmap_buffer_size, PROT_READ | PROT_WRITE,
 		   mmap_flags, -1, 0);
 	assert(vrc == self->buffer);
 
@@ -2066,8 +2084,8 @@ FIXTURE_SETUP(iommufd_dirty_tracking)
 
 FIXTURE_TEARDOWN(iommufd_dirty_tracking)
 {
-	munmap(self->buffer, variant->buffer_size);
-	munmap(self->bitmap, DIV_ROUND_UP(self->bitmap_size, BITS_PER_BYTE));
+	free(self->buffer);
+	free(self->bitmap);
 	teardown_iommufd(self->fd, _metadata);
 }
 

tools/testing/selftests/iommu/iommufd_utils.h

@@ -60,13 +60,18 @@ static inline void *memfd_mmap(size_t length, int prot, int flags, int *mfd_p)
 {
 	int mfd_flags = (flags & MAP_HUGETLB) ? MFD_HUGETLB : 0;
 	int mfd = memfd_create("buffer", mfd_flags);
+	void *buf = MAP_FAILED;
 
 	if (mfd <= 0)
 		return MAP_FAILED;
 	if (ftruncate(mfd, length))
-		return MAP_FAILED;
+		goto out;
 	*mfd_p = mfd;
-	return mmap(0, length, prot, flags, mfd, 0);
+	buf = mmap(0, length, prot, flags, mfd, 0);
+out:
+	if (buf == MAP_FAILED)
+		close(mfd);
+	return buf;
 }
 
 /*