Re: [PATCH 1/3] mm: get_cmdline use arg_lock instead of mmap_sem

[Michal Koutný]

On Tue, Apr 30, 2019 at 01:45:17PM +0300, Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote:
> It setups these parameters unconditionally. I need to revisit
> this moment. Technically (if only I'm not missing something
> obvious) we might have a race here with prctl setting up new
> params, but this should be harmless since most of them (except
> stack setup) are purely informative data.
FTR, when I reviewed that usage, I noticed it was missing the
synchronization. My understanding was that the mm_struct isn't yet
shared at this moment. I can see some of the operations take place after
flush_old_exec (where current->mm = mm_struct), so potentially it is
shared since then. OTOH, I guess there aren't concurrent parties that
could access the field at this stage of exec.

My 2 cents,
Michal

Attachment: signature.asc
Description: Digital signature