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Groups > linux.kernel > #1736104 > unrolled thread
| Started by | Kees Cook <keescook@chromium.org> |
|---|---|
| First post | 2017-09-20 22:50 +0200 |
| Last post | 2017-09-20 22:50 +0200 |
| Articles | 1 — 1 participant |
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[PATCH v3 06/31] vfs: Copy struct mount.mnt_id to userspace using put_user() Kees Cook <keescook@chromium.org> - 2017-09-20 22:50 +0200
| From | Kees Cook <keescook@chromium.org> |
|---|---|
| Date | 2017-09-20 22:50 +0200 |
| Subject | [PATCH v3 06/31] vfs: Copy struct mount.mnt_id to userspace using put_user() |
| Message-ID | <urU6v-818-23@gated-at.bofh.it> |
From: David Windsor <dave@nullcore.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@nullcore.net> [kees: adjust commit log] Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- fs/fhandle.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/fs/fhandle.c b/fs/fhandle.c index 58a61f55e0d0..46e00ccca8f0 100644 --- a/fs/fhandle.c +++ b/fs/fhandle.c @@ -68,8 +68,7 @@ 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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