Date: Mon, 21 Apr 2014 08:20:22 +0200
From: Maxime Villard <max%M00nBSD.net@localhost>
Le 21/04/2014 01:46, Taylor R Campbell a écrit :
> In most cases of the changes you made, there is already a test for the
> length of the data buffer. Is this not guaranteed to be zero if data
> is null? It seems to me that the length test ought to suffice, and if
> anything the null pointer test should be an assertion, not a check.
Not at all. 'data' and 'data_len' come from userpace. A user can set data
to NULL and data_len to a value high enough to bypass the data_len check.
If a user passes in null data and nonzero data_len, why doesn't
mount(2) just return EINVAL?
Giving file systems the responsibility for basic sanity checks on
syscall arguments strikes me as error-prone.