Re: [PATCH 3/9] fs: explicitly check for CHECK_IOVEC_ONLY in rw_copy_check_uvector

[Johannes Thumshirn]

Looks good,
Reviewed-by: Johannes Thumshirn 

Re: [PATCH 3/9] fs: explicitly check for CHECK_IOVEC_ONLY in rw_copy_check_uvector

[Matthew Wilcox]

On Fri, Sep 18, 2020 at 02:45:27PM +0200, Christoph Hellwig wrote:
>   }
> - if (type >= 0
> - && unlikely(!access_ok(buf, len))) {
> + if (type != CHECK_IOVEC_ONLY && unlikely(!access_ok(buf, len))) 
> {

drop the unlikely() at the same time?  if it's really advantageous,
that should be embedded in the access_ok macro.

[PATCH 3/9] fs: explicitly check for CHECK_IOVEC_ONLY in rw_copy_check_uvector

[Christoph Hellwig]

Explicitly check for the magic value insted of implicitly relying on
its number representation.

Signed-off-by: Christoph Hellwig 
---
 fs/read_write.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index 5db58b8c78d0dd..f153116bc5399b 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -840,8 +840,7 @@ ssize_t rw_copy_check_uvector(int type, const struct iovec 
__user * uvector,
ret = -EINVAL;
goto out;
}
-   if (type >= 0
-   && unlikely(!access_ok(buf, len))) {
+   if (type != CHECK_IOVEC_ONLY && unlikely(!access_ok(buf, len))) 
{
ret = -EFAULT;
goto out;
}
@@ -911,7 +910,7 @@ ssize_t compat_rw_copy_check_uvector(int type,
}
if (len < 0)/* size_t not fitting in compat_ssize_t .. */
goto out;
-   if (type >= 0 &&
+   if (type != CHECK_IOVEC_ONLY &&
!access_ok(compat_ptr(buf), len)) {
ret = -EFAULT;
goto out;
-- 
2.28.0