linux-ext4 - [PATCH 8/9] fs: remove the access_ok() check in ioctl

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Date:   Sat, 23 May 2020 09:30:15 +0200
From:   Christoph Hellwig <hch@....de>
To:     linux-ext4@...r.kernel.org, viro@...iv.linux.org.uk
Cc:     jack@...e.cz, tytso@....edu, adilger@...ger.ca,
        riteshh@...ux.ibm.com, amir73il@...il.com,
        linux-fsdevel@...r.kernel.org, linux-unionfs@...r.kernel.org,
        "Darrick J . Wong" <darrick.wong@...cle.com>
Subject: [PATCH 8/9] fs: remove the access_ok() check in ioctl_fiemap

access_ok just checks we are fed a proper user pointer.  We also do that
in copy_to_user itself, so no need to do this early.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Ritesh Harjani <riteshh@...ux.ibm.com>
Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>
---
 fs/ioctl.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/fs/ioctl.c b/fs/ioctl.c
index b16e962340db6..d69786d1dd911 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -213,13 +213,9 @@ static int ioctl_fiemap(struct file *filp, struct fiemap __user *ufiemap)
 	fieinfo.fi_extents_max = fiemap.fm_extent_count;
 	fieinfo.fi_extents_start = ufiemap->fm_extents;
 
-	if (fiemap.fm_extent_count != 0 &&
-	    !access_ok(fieinfo.fi_extents_start,
-		       fieinfo.fi_extents_max * sizeof(struct fiemap_extent)))
-		return -EFAULT;
-
 	error = inode->i_op->fiemap(inode, &fieinfo, fiemap.fm_start,
 			fiemap.fm_length);
+
 	fiemap.fm_flags = fieinfo.fi_flags;
 	fiemap.fm_mapped_extents = fieinfo.fi_extents_mapped;
 	if (copy_to_user(ufiemap, &fiemap, sizeof(fiemap)))
-- 
2.26.2