Messages in this thread | | | Date | Fri, 16 Jan 2015 12:24:04 -0800 | From | Andrew Morton <> | Subject | Re: Issue with 'lib/vsprintf.c: don't try to fix pointer wrap-around' |
| |
On Fri, 16 Jan 2015 11:23:57 -0500 Johannes Weiner <hannes@cmpxchg.org> wrote:
> Hi Rasmus, > > I have trouble booting my test machine with this patch in -mm: > > commit bb2e066c6943e62e9650bb129f416dacf138f8b1 > Author: Rasmus Villemoes <linux@rasmusvillemoes.dk> > Date: Wed Jan 14 01:00:44 2015 +0000 > > lib/vsprintf.c: don't try to fix pointer wrap-around > > Actual kernel buffers can't wrap into the user address space. If someone > manages to pass a buf/size combination that wraps, it is most likely due > to a bug in the caller. Instead of trying to fix it by using a smaller > part of the buffer, bail out. > > Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> > Cc: Jiri Kosina <jkosina@suse.cz> > Cc: Randy Dunlap <rdunlap@infradead.org> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > > After I get "Loading bzImage-new... ok" from the bootloader, the > serial console remains quiet. > > A WARN_ON_ONCE() inside vsnprintf() looks like it would deadlock > instantly when triggering this overflow from printk(), no?
Dammit, I was starting at that printk, ended up deciding it was OK, didn't think about deadlocks. logbuf_lock and recursion_bug, for a start...
I'll drop the patch. I assume all this means that your machine is trying to trigger that warning condition? I wonder what the call site is.
| |