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authorDavid Windsor <dave@nullcore.net>2017-06-10 22:50:31 -0400
committerKees Cook <keescook@chromium.org>2018-01-15 12:07:51 -0800
commit6391af6f5829e8767c6d5e777194c9ecdd5d7ead (patch)
tree4dd61723d47a6787476883d404d128436bd87b16
parent6a9b88204cb00da2140afda27848b5d17a7402a3 (diff)
vfs: Copy struct mount.mnt_id to userspace using put_user()
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>
-rw-r--r--fs/fhandle.c3
1 files changed, 1 insertions, 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;