Re: NULL pointer dereference in the kernel 3.10

[Willy Tarreau]

On Mon, Apr 10, 2017 at 10:33:56PM +0800, zhong jiang wrote:
> On 2017/4/10 22:13, Willy Tarreau wrote:
> > On Mon, Apr 10, 2017 at 10:06:59PM +0800, zhong jiang wrote:
> >> On 2017/4/10 20:48, Michal Hocko wrote:
> >>> On Mon 10-04-17 20:10:06, zhong jiang wrote:
> >>>> On 2017/4/10 16:56, Mel Gorman wrote:
> >>>>> On Sat, Apr 08, 2017 at 09:39:42PM +0800, zhong jiang wrote:
> >>>>>> when runing the stabile docker cases in the vm.   The following issue will come up.
> >>>>>>
> >>>>>> #40 [ffff8801b57ffb30] async_page_fault at ffffffff8165c9f8
> >>>>>>     [exception RIP: down_read_trylock+5]
> >>>>>>     RIP: ffffffff810aca65  RSP: ffff8801b57ffbe8  RFLAGS: 00010202
> >>>>>>     RAX: 0000000000000000  RBX: ffff88018ae858c1  RCX: 0000000000000000
> >>>>>>     RDX: 0000000000000000  RSI: 0000000000000000  RDI: 0000000000000008
> >>>>>>     RBP: ffff8801b57ffc10   R8: ffffea0006903de0   R9: ffff8800b3c61810
> >>>>>>     R10: 00000000000022cb  R11: 0000000000000000  R12: ffff88018ae858c0
> >>>>>>     R13: ffffea0006903dc0  R14: 0000000000000008  R15: ffffea0006903dc0
> >>>>>>     ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0000
> >>>>> Post the full report including the kernel version and state whether any
> >>>>> additional patches to 3.10 are applied.
> >>>>>
> >>>>  Hi, Mel
> >>>>    
> >>>>         Our kernel from RHEL 7.2, Addtional patches all from upstream -- include Bugfix and CVE.
> >>> I believe you should contact Redhat for the support. This is a) old
> >>> kernel and b) with other patches which might or might not be relevant.
> >>   Ok, regardless of the kernel version, we just discuss the situation in theory.  if commit
> >>   624483f3ea8  ("mm: rmap: fix use-after-free in __put_anon_vma")  is not exist. the issue
> >>  will trigger . Any thought.
> > But this commit was backported into 3.10.43, so stable kernel users are safe.
> >
> > Regards,
> > Willy
> >
> > .
>   yes,  you are sure that the commit can fix the issue.

No, I have absolutely no opinion on either the commit nor the bug, what
I'm saying is that any up-to-date 3.10 contains the commit you mentionned,
so if that's the fix, you just need to ensure your kernel is up to date,
that's all.

Willy