[v15,10/17] fs, arm64: untag user pointers in fs/userfaultfd.c
diff mbox series

Message ID 30b44d469bb545c608531faf01fb10248ed78887.1557160186.git.andreyknvl@google.com
State New
Headers show
Series
  • arm64: untag user pointers passed to the kernel
Related show

Commit Message

Andrey Konovalov May 6, 2019, 4:30 p.m. UTC
This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

userfaultfd code use provided user pointers for vma lookups, which can
only by done with untagged pointers.

Untag user pointers in validate_range().

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 fs/userfaultfd.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

Patch
diff mbox series

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index f5de1e726356..aa47ed0969dd 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1261,21 +1261,23 @@  static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx,
 }
 
 static __always_inline int validate_range(struct mm_struct *mm,
-					  __u64 start, __u64 len)
+					  __u64 *start, __u64 len)
 {
 	__u64 task_size = mm->task_size;
 
-	if (start & ~PAGE_MASK)
+	*start = untagged_addr(*start);
+
+	if (*start & ~PAGE_MASK)
 		return -EINVAL;
 	if (len & ~PAGE_MASK)
 		return -EINVAL;
 	if (!len)
 		return -EINVAL;
-	if (start < mmap_min_addr)
+	if (*start < mmap_min_addr)
 		return -EINVAL;
-	if (start >= task_size)
+	if (*start >= task_size)
 		return -EINVAL;
-	if (len > task_size - start)
+	if (len > task_size - *start)
 		return -EINVAL;
 	return 0;
 }
@@ -1325,7 +1327,7 @@  static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 		goto out;
 	}
 
-	ret = validate_range(mm, uffdio_register.range.start,
+	ret = validate_range(mm, &uffdio_register.range.start,
 			     uffdio_register.range.len);
 	if (ret)
 		goto out;
@@ -1514,7 +1516,7 @@  static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 	if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister)))
 		goto out;
 
-	ret = validate_range(mm, uffdio_unregister.start,
+	ret = validate_range(mm, &uffdio_unregister.start,
 			     uffdio_unregister.len);
 	if (ret)
 		goto out;
@@ -1665,7 +1667,7 @@  static int userfaultfd_wake(struct userfaultfd_ctx *ctx,
 	if (copy_from_user(&uffdio_wake, buf, sizeof(uffdio_wake)))
 		goto out;
 
-	ret = validate_range(ctx->mm, uffdio_wake.start, uffdio_wake.len);
+	ret = validate_range(ctx->mm, &uffdio_wake.start, uffdio_wake.len);
 	if (ret)
 		goto out;
 
@@ -1705,7 +1707,7 @@  static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
 			   sizeof(uffdio_copy)-sizeof(__s64)))
 		goto out;
 
-	ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len);
+	ret = validate_range(ctx->mm, &uffdio_copy.dst, uffdio_copy.len);
 	if (ret)
 		goto out;
 	/*
@@ -1761,7 +1763,7 @@  static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx,
 			   sizeof(uffdio_zeropage)-sizeof(__s64)))
 		goto out;
 
-	ret = validate_range(ctx->mm, uffdio_zeropage.range.start,
+	ret = validate_range(ctx->mm, &uffdio_zeropage.range.start,
 			     uffdio_zeropage.range.len);
 	if (ret)
 		goto out;