tree 03b54e12af45ca97641f8d86113c67b5a929b006
parent f18c34e483ff6b1d9866472221e4015b3a4698e4
author Sasha Levin <sasha.levin@oracle.com> 1422477043 -0500
committer Linus Torvalds <torvalds@linux-foundation.org> 1433266147 -0700

vfs: read file_handle only once in handle_to_path

We used to read file_handle twice.  Once to get the amount of extra
bytes, and once to fetch the entire structure.

This may be problematic since we do size verifications only after the
first read, so if the number of extra bytes changes in userspace between
the first and second calls, we'll have an incoherent view of
file_handle.

Instead, read the constant size once, and copy that over to the final
structure without having to re-read it again.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>