Arnd Bergmann wrote:
On Tuesday 14 November 2006 00:58, [email protected] wrote:
Subject: Fix compat space msg size limit for msgsnd/msgrcv
From: suzuki <[email protected]>
Currently we allocate 64k space on the user stack and use it the msgbuf for
sys_{msgrcv,msgsnd} for compat and the results are later copied in user [by
copy_in_user].
This patch introduces helper routines for sys_{msgrcv,msgsnd} which would
accept the pointer to msgbuf along with the msgp->mtext. This avoids the
need to allocate the msgsize on the userspace (thus removing the size
limit) and the overhead of an extra copy_in_user().
Signed-off-by: Suzuki K P <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: "David S. Miller" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
This patch is definitely a big step in the right direction here, but why
not go all the way and pass msgp->mtype to do_msgsnd/do_msgrcv as kernel
data instead of a user space pointer? This way you can get rid of the
compat_alloc_userspace entirely and save avoid doing an extra
put_user/get_user pair in the compat_ function.
I left it as such, inorder to avoid the future changes that may come in
the struct msgbuf -if at all-, which would make us to pass every single
field as a parameter to do_msgrcv/do_msgsnd.
thanks,
Suzuki
Arnd <><
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