mm: kmsan: handle alloc failures in kmsan_vmap_pages_range_noflush()

As reported by Dipanjan Das, when KMSAN is used together with kernel fault
injection (or, generally, even without the latter), calls to kcalloc() or
__vmap_pages_range_noflush() may fail, leaving the metadata mappings for
the virtual mapping in an inconsistent state.  When these metadata
mappings are accessed later, the kernel crashes.

To address the problem, we return a non-zero error code from
kmsan_vmap_pages_range_noflush() in the case of any allocation/mapping
failure inside it, and make vmap_pages_range_noflush() return an error if
KMSAN fails to allocate the metadata.

This patch also removes KMSAN_WARN_ON() from vmap_pages_range_noflush(),
as these allocation failures are not fatal anymore.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: b073d7f8aee4 ("mm: kmsan: maintain KMSAN metadata for page operations")
Signed-off-by: Alexander Potapenko <[email protected]>
Reported-by: Dipanjan Das <[email protected]>
  Link: https://lore.kernel.org/linux-mm/CANX2M5ZRrRA64k0hOif02TjmY9kbbO2aCBPyq79es34RXZ=cAw@mail.gmail.com/
Reviewed-by: Marco Elver <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Uladzislau Rezki (Sony) <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 5 insertions, 1 deletions

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a50072066221..1355d95cce1c 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -605,7 +605,11 @@ int __vmap_pages_range_noflush(unsigned long addr, unsigned long end,
 int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
 		pgprot_t prot, struct page **pages, unsigned int page_shift)
 {
-	kmsan_vmap_pages_range_noflush(addr, end, prot, pages, page_shift);
+	int ret = kmsan_vmap_pages_range_noflush(addr, end, prot, pages,
+						 page_shift);
+
+	if (ret)
+		return ret;
 	return __vmap_pages_range_noflush(addr, end, prot, pages, page_shift);
 }