| Message ID | 20210818060533.3569517-51-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Introduce strict memcpy() bounds checking | expand |
On Tue, 17 Aug 2021 23:05:20 -0700 Kees Cook <keescook@chromium.org> wrote: > In preparation for FORTIFY_SOURCE performing compile-time and run-time > field bounds checking for memset(), avoid intentionally writing across > neighboring fields. > > Use memset_startat() to avoid confusing memset() about writing beyond > the target struct member. > > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Ingo Molnar <mingo@redhat.com> > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > kernel/trace/trace.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 13587e771567..9ff8c31975cd 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -6691,9 +6691,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, > cnt = PAGE_SIZE - 1; > > /* reset all but tr, trace, and overruns */ > - memset(&iter->seq, 0, > - sizeof(struct trace_iterator) - > - offsetof(struct trace_iterator, seq)); > + memset_startat(iter, 0, seq); I can't find memset_startat() in mainline nor linux-next. I don't see it in this thread either, but since this has 63 patches, I could have easily missed it. This change really should belong to a patch set that just introduces memset_startat() (and perhaps memset_after()) and then updates all the places that should use it. That way I can give it a proper review. In other words, you should break this patch set up into smaller, more digestible portions for the reviewers. Thanks, -- Steve > cpumask_clear(iter->started); > trace_seq_init(&iter->seq); > iter->pos = -1;
On Wed, Aug 18, 2021 at 09:33:49AM -0400, Steven Rostedt wrote: > On Tue, 17 Aug 2021 23:05:20 -0700 > Kees Cook <keescook@chromium.org> wrote: > > > In preparation for FORTIFY_SOURCE performing compile-time and run-time > > field bounds checking for memset(), avoid intentionally writing across > > neighboring fields. > > > > Use memset_startat() to avoid confusing memset() about writing beyond > > the target struct member. > > > > Cc: Steven Rostedt <rostedt@goodmis.org> > > Cc: Ingo Molnar <mingo@redhat.com> > > Signed-off-by: Kees Cook <keescook@chromium.org> > > --- > > kernel/trace/trace.c | 4 +--- > > 1 file changed, 1 insertion(+), 3 deletions(-) > > > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > > index 13587e771567..9ff8c31975cd 100644 > > --- a/kernel/trace/trace.c > > +++ b/kernel/trace/trace.c > > @@ -6691,9 +6691,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, > > cnt = PAGE_SIZE - 1; > > > > /* reset all but tr, trace, and overruns */ > > - memset(&iter->seq, 0, > > - sizeof(struct trace_iterator) - > > - offsetof(struct trace_iterator, seq)); > > + memset_startat(iter, 0, seq); > > I can't find memset_startat() in mainline nor linux-next. I don't see it > in this thread either, but since this has 63 patches, I could have > easily missed it. Sorry, it isn't called out in the Subject, but it's part of this patch: https://lore.kernel.org/lkml/20210818060533.3569517-38-keescook@chromium.org/ > This change really should belong to a patch set that just introduces > memset_startat() (and perhaps memset_after()) and then updates all the > places that should use it. That way I can give it a proper review. In > other words, you should break this patch set up into smaller, more > digestible portions for the reviewers. I will split memset_after() and memset_startat() introduction patches. I already split up each use into individual cases, so that those changes could be checked one step at a time for differences in pahole struct layout and object code. Thanks for taking a look! -Kees
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 13587e771567..9ff8c31975cd 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6691,9 +6691,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, cnt = PAGE_SIZE - 1; /* reset all but tr, trace, and overruns */ - memset(&iter->seq, 0, - sizeof(struct trace_iterator) - - offsetof(struct trace_iterator, seq)); + memset_startat(iter, 0, seq); cpumask_clear(iter->started); trace_seq_init(&iter->seq); iter->pos = -1;
In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memset(), avoid intentionally writing across neighboring fields. Use memset_startat() to avoid confusing memset() about writing beyond the target struct member. Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Kees Cook <keescook@chromium.org> --- kernel/trace/trace.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)