The patch titled
Subject: dax: explain how read(2)/write(2) addresses are validated
has been removed from the -mm tree. Its filename was
dax-explain-how-read2-write2-addresses-are-validated.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Subject: dax: explain how read(2)/write(2) addresses are validated
Add a comment explaining how the user addresses provided to read(2) and
write(2) are validated in the DAX I/O path. We call dax_copy_from_iter()
or copy_to_iter() on these without calling access_ok() first in the DAX
code, and there was a concern that the user might be able to read/write to
arbitrary kernel addresses with this path.
Link: http://lkml.kernel.org/r/20170816173615.10098-1-ross.zwisler@xxxxxxxxxxxxxxx
Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/dax.c | 5 +++++
1 file changed, 5 insertions(+)
diff -puN fs/dax.c~dax-explain-how-read2-write2-addresses-are-validated fs/dax.c
--- a/fs/dax.c~dax-explain-how-read2-write2-addresses-are-validated
+++ a/fs/dax.c
@@ -1004,6 +1004,11 @@ dax_iomap_actor(struct inode *inode, lof
if (map_len > end - pos)
map_len = end - pos;
+ /*
+ * The userspace address for the memory copy has already been
+ * validated via access_ok() in either vfs_read() or
+ * vfs_write(), depending on which operation we are doing.
+ */
if (iov_iter_rw(iter) == WRITE)
map_len = dax_copy_from_iter(dax_dev, pgoff, kaddr,
map_len, iter);
_
Patches currently in -mm which might be from ross.zwisler@xxxxxxxxxxxxxxx are
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
