[PATCH v2] iommu/vt-d: Fix copied_tables bitmap leak on error in copy_translation_tables

[ZhaoJinming <zhaojinming@uniontech.com>]

The iommu->copied_tables bitmap was introduced by the IOMMU live
update series to track which context entries have been copied from
the previous kernel.  The allocation via bitmap_zalloc() was added
inside copy_translation_tables(), but the error paths were not
updated to free it:

  1. When old_rt_phys is 0 (invalid root table address)
  2. When memremap(old_rt_phys) fails
  3. When kcalloc for ctxt_tbls fails (goto out_unmap, which only
     unmaps old_rt without releasing the bitmap)

The bitmap is only cleaned up by free_dmar_iommu(), which is
called from the free_iommu error label in init_dmars().  However,
when copy_translation_tables() fails, init_dmars() does not jump
to free_iommu -- it logs the error, falls through, and continues
with the next IOMMU.  As a result, copied_tables is leaked.

Fix this by converting the two early returns to goto a new
err_free_bitmap label, and by making out_unmap fall through to
it so that the bitmap is always freed on any error path.  The
success path performs memunmap(old_rt) inline and returns 0
directly, since copied_tables must remain allocated for
subsequent use.
---

v2:
- On the success path, call memunmap(old_rt) before returning 0
  instead of returning directly, fixing a memunmap leak introduced
  in v1.  Suggested by Baolu Lu.

Signed-off-by: ZhaoJinming <zhaojinming@uniontech.com>
---
 drivers/iommu/intel/iommu.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 849d06dfe1ae..05376a7231a0 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1554,12 +1554,16 @@ static int copy_translation_tables(struct intel_iommu *iommu)
 		return -ENOMEM;
 
 	old_rt_phys = rtaddr_reg & VTD_PAGE_MASK;
-	if (!old_rt_phys)
-		return -EINVAL;
+	if (!old_rt_phys) {
+		ret = -EINVAL;
+		goto err_free_bitmap;
+	}
 
 	old_rt = memremap(old_rt_phys, PAGE_SIZE, MEMREMAP_WB);
-	if (!old_rt)
-		return -ENOMEM;
+	if (!old_rt) {
+		ret = -ENOMEM;
+		goto err_free_bitmap;
+	}
 
 	/* This is too big for the stack - allocate it from slab */
 	ctxt_table_entries = ext ? 512 : 256;
@@ -1603,11 +1607,14 @@ static int copy_translation_tables(struct intel_iommu *iommu)
 
 	__iommu_flush_cache(iommu, iommu->root_entry, PAGE_SIZE);
 
-	ret = 0;
+	memunmap(old_rt);
+	return 0;
 
 out_unmap:
 	memunmap(old_rt);
-
+err_free_bitmap:
+	bitmap_free(iommu->copied_tables);
+	iommu->copied_tables = NULL;
 	return ret;
 }
 
-- 
2.20.1