Messages in this thread | | | From | Linus Torvalds <> | Date | Sat, 20 Jun 2020 09:32:26 -0700 | Subject | Re: [tip: sched/urgent] sched: Fix RANDSTRUCT build fail |
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On Fri, Jun 19, 2020 at 8:14 PM Kees Cook <keescook@chromium.org> wrote: > > On Wed, Jun 10, 2020 at 10:34:16AM -0000, tip-bot2 for Peter Zijlstra wrote: > > The following commit has been merged into the sched/urgent branch of tip: > > > > Commit-ID: bfb9fbe0f7e70ec5c8e51ee55b6968d4dff14456 > > Gitweb: https://git.kernel.org/tip/bfb9fbe0f7e70ec5c8e51ee55b6968d4dff14456 > > Author: Peter Zijlstra <peterz@infradead.org> > > AuthorDate: Wed, 10 Jun 2020 12:14:09 +02:00 > > Committer: Peter Zijlstra <peterz@infradead.org> > > CommitterDate: Wed, 10 Jun 2020 12:30:19 +02:00 > > > > sched: Fix RANDSTRUCT build fail > > > > As a temporary build fix, the proper cleanup needs more work. > > > > Reported-by: Guenter Roeck <linux@roeck-us.net> > > Reported-by: Eric Biggers <ebiggers@kernel.org> > > Suggested-by: Eric Biggers <ebiggers@kernel.org> > > Suggested-by: Kees Cook <keescook@chromium.org> > > Fixes: a148866489fb ("sched: Replace rq::wake_list") > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > > Hi, can this please get sent to Linus before -rc2? With a148866489fb in > -rc1, all the CI with the GCC plugins installed have been failing their > all*config builds. This entered -next 9 days ago (and fixed the -next > builds), but Linus's tree is still failing:
Ugh.
I actually think the problem goes deeper than that.
The code expects the list entries to be of type 'call_single_data_t'
Then they damn well should be that type.
Note how "call_single_data_t" also implies certain alignment rules that the hack in 'struct task_struct' does *not* have, and while that doesn't matter on x86, it could matter on other architectures.
So no, I don't think Peter's patch is correct. It may make the build pass, but that "check the offsets between two fields" is not sufficient.
Now, if we could create a new
struct __call_single_list_entry { struct llist_node llist; unsigned int flags; } call_single_list_entry_t;
and use that as part of thecall_single_data_t and only use that for tyhe traversal of the list, then that would avoid the alignment issue and the waste of space in struct task_struct.
Hmm?
Peter/Ingo?
Linus
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