Re: [PATCH 1/3] ipc: sysvsem: implement sys_unshare(CLONE_SYSVSEM)

[Eric W. Biederman]

"Serge E. Hallyn" <serue@xxxxxxxxxx> writes:

> (patches 1 and 2 were originally by Manfred Spraul)
>
> sys_unshare(CLONE_NEWIPC) doesn't handle the undo lists properly, this can
> cause a kernel memory corruption. CLONE_NEWIPC must detach from the existing
> undo lists.
>
> Fix, part 1: add support for sys_unshare(CLONE_SYSVSEM)
>
> The original reason to not support it was the potential (inevitable?)
> confusion due to the fact that sys_unshare(CLONE_SYSVSEM) has the
> inverse meaning of clone(CLONE_SYSVSEM).
>
> Our two most reasonable options then appear to be (1) fully support
> CLONE_SYSVSEM, or (2) continue to refuse explicit CLONE_SYSVSEM,
> but always do it anyway on unshare(CLONE_SYSVSEM).  This patch does
> (1).
>
> Changelog:
> 	Apr 16: SEH: switch to Manfred's alternative patch which
> 		removes the unshare_semundo() function which
> 		always refused CLONE_SYSVSEM.
>
> Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
> Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>

These patches look like the fix the core issue.

Acked-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>

Eric
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