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Date: Wed, 10 Jan 2018 18:02:44 -0800
From: Kees Cook <keescook@...omium.org>
To: linux-kernel@...r.kernel.org
Cc: Kees Cook <keescook@...omium.org>,
David Windsor <dave@...lcore.net>,
Alexander Viro <viro@...iv.linux.org.uk>,
linux-fsdevel@...r.kernel.org,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Andy Lutomirski <luto@...nel.org>,
Christoph Hellwig <hch@...radead.org>,
Christoph Lameter <cl@...ux.com>,
"David S. Miller" <davem@...emloft.net>,
Laura Abbott <labbott@...hat.com>,
Mark Rutland <mark.rutland@....com>,
"Martin K. Petersen" <martin.petersen@...cle.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Christian Borntraeger <borntraeger@...ibm.com>,
Christoffer Dall <christoffer.dall@...aro.org>,
Dave Kleikamp <dave.kleikamp@...cle.com>,
Jan Kara <jack@...e.cz>,
Luis de Bethencourt <luisbg@...nel.org>,
Marc Zyngier <marc.zyngier@....com>,
Rik van Riel <riel@...hat.com>,
Matthew Garrett <mjg59@...gle.com>,
linux-arch@...r.kernel.org,
netdev@...r.kernel.org,
linux-mm@...ck.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH 12/38] vfs: Copy struct mount.mnt_id to userspace using put_user()
From: David Windsor <dave@...lcore.net>
The mnt_id field can be copied with put_user(), so there is no need to
use copy_to_user(). In both cases, hardened usercopy is being bypassed
since the size is constant, and not open to runtime manipulation.
This patch is verbatim from Brad Spengler/PaX Team's PAX_USERCOPY
whitelisting code in the last public patch of grsecurity/PaX based on my
understanding of the code. Changes or omissions from the original code are
mine and don't reflect the original grsecurity/PaX code.
Signed-off-by: David Windsor <dave@...lcore.net>
[kees: adjust commit log]
Cc: Alexander Viro <viro@...iv.linux.org.uk>
Cc: linux-fsdevel@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
fs/fhandle.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/fs/fhandle.c b/fs/fhandle.c
index 0ace128f5d23..0ee727485615 100644
--- a/fs/fhandle.c
+++ b/fs/fhandle.c
@@ -69,8 +69,7 @@ static long do_sys_name_to_handle(struct path *path,
} else
retval = 0;
/* copy the mount id */
- if (copy_to_user(mnt_id, &real_mount(path->mnt)->mnt_id,
- sizeof(*mnt_id)) ||
+ if (put_user(real_mount(path->mnt)->mnt_id, mnt_id) ||
copy_to_user(ufh, handle,
sizeof(struct file_handle) + handle_bytes))
retval = -EFAULT;
--
2.7.4
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