On Tue, 20 Jan 2015 19:49:47 +0800
Junxiao Bi <junxiao.bi@xxxxxxxxxx> wrote:
> On 01/19/2015 10:29 PM, Jeff Layton wrote:
> > On Mon, 19 Jan 2015 09:17:51 +0800
> > Junxiao Bi <junxiao.bi@xxxxxxxxxx> wrote:
> >
> >> On 01/18/2015 10:43 PM, Trond Myklebust wrote:
> >>> On Sun, Jan 18, 2015 at 7:29 AM, Junxiao Bi <junxiao.bi@xxxxxxxxxx> wrote:
> >>>> nfsd4_decode_open() doesn't initialize variable open->op_file and
> >>>> open->op_stp, they are initialized in nfsd4_process_open1(), but if
> >>>> any error happens before initializing them, nfsd4_open() will call
> >>>> into nfsd4_cleanup_open_state() and corrupt the memory.
> >>>>
> >>>> Since nfsd4_process_open1() will initialize these two variables and
> >>>> open->op_openowner, make them default to null at the beginning.
> >>>>
> >>>> Signed-off-by: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
> >>>> ---
> >>>> fs/nfsd/nfs4state.c | 4 ++++
> >>>> 1 file changed, 4 insertions(+)
> >>>>
> >>>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> >>>> index c06a1ba..6e74a91 100644
> >>>> --- a/fs/nfsd/nfs4state.c
> >>>> +++ b/fs/nfsd/nfs4state.c
> >>>> @@ -3547,6 +3547,10 @@ nfsd4_process_open1(struct nfsd4_compound_state *cstate,
> >>>> struct nfs4_openowner *oo = NULL;
> >>>> __be32 status;
> >>>>
> >>>> + open->op_file = NULL;
> >>>> + open->op_openowner = NULL;
> >>>> + open->op_stp = NULL;
> >>>> +
> >>>> if (STALE_CLIENTID(&open->op_clientid, nn))
> >>>> return nfserr_stale_clientid;
> >>>> /*
> >>> Have you ever seen an instance of this corruption? I would have
> >>> thought that the kzalloc() in nfsd4_decode_compound() and/or the
> >>> earlier memset() in svc_process_common() would ensure that these
> >>> fields are always initialised to NULL.
> >> Yes, we got the following panic from 3.8.13. The bad pointer
> >> open->op_stp was freed into kmem_cache array_cache, and was allocated to
> >> next "op_stp" allocation request which triggered the panic.
> >>
> >>
> >> @ PID: 21663 TASK: ffff8809fe6103c0 CPU: 0 COMMAND: "nfsd"
> >> @ #0 [ffff8809fe613980] machine_kexec at ffffffff810421d9
> >> @ #1 [ffff8809fe6139f0] crash_kexec at ffffffff810c9d39
> >> @ #2 [ffff8809fe613ac0] oops_end at ffffffff81599298
> >> @ #3 [ffff8809fe613af0] die at ffffffff8101870b
> >> @ #4 [ffff8809fe613b20] do_general_protection at ffffffff8159906c
> >> @ #5 [ffff8809fe613b50] general_protection at ffffffff81598668
> >> @ [exception RIP: init_stid+14]
> >> @ RIP: ffffffffa058247e RSP: ffff8809fe613c08 RFLAGS: 00010292
> >> @ RAX: 0000000000000000 RBX: 736e61727465722c RCX: 0000000000000000
> >> @ RDX: 0000000000000001 RSI: ffff8808e433a800 RDI: 736e61727465722c
> >> @ RBP: ffff8809fe613c28 R8: ffff880a01469000 R9: 0000000000000000
> >> @ R10: 0000000000000000 R11: 0000000000000000 R12: ffff8808e19821a0
> >> @ R13: ffff8809aa40f3a8 R14: ffff8809fd781040 R15: ffff8809aafc9c98
> >> @ ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
> >> @ #6 [ffff8809fe613c30] nfsd4_process_open2 at ffffffffa0588123 [nfsd]
> >> @ #7 [ffff8809fe613d00] nfsd4_open at ffffffffa0577e82 [nfsd]
> >> @ #8 [ffff8809fe613d50] nfsd4_proc_compound at ffffffffa0575de8 [nfsd]
> >> @ #9 [ffff8809fe613db0] nfsd_dispatch at ffffffffa056429b [nfsd]
> >> @ #10 [ffff8809fe613df0] svc_process_common at ffffffffa04afd14 [sunrpc]
> >> @ #11 [ffff8809fe613e70] svc_process at ffffffffa04b034f [sunrpc]
> >> @ #12 [ffff8809fe613e90] nfsd at ffffffffa05649ff [nfsd]
> >> @ #13 [ffff8809fe613ec0] kthread at ffffffff81082f4e
> >> @ #14 [ffff8809fe613f50] ret_from_fork at ffffffff815a09ac
> >>
> >> Thanks,
> >> Junxiao.
> >>
> >>> Cheers
> >>> Trond
> >>>
> > I agree with Trond. This patch doesn't make much sense.
> >
> > Why isn't that memset in svc_process_common() zeroing this out? If this
> > is a bug in the open codepath, then it's almost certainly a bug for
> > other compound ops. I'd suggest doing a bit more investigative work and
> > see if you can figure out why that isn't working as expected...
> Found the cause, this issue should have been fix by the following
> commit. This fix is not merged in 3.8.13. Thanks for you and Trond
> review it.
>
> commit 5d6031ca742f9f07b9c9d9322538619f3bd155ac
> Author: J. Bruce Fields <bfields@xxxxxxxxxx>
> Date: Thu Jul 17 16:20:39 2014 -0400
>
> nfsd4: zero op arguments beyond the 8th compound op
>
> The first 8 ops of the compound are zeroed since they're a part of the
> argument that's zeroed by the
>
> memset(rqstp->rq_argp, 0, procp->pc_argsize);
>
> in svc_process_common(). But we handle larger compounds by allocating
> the memory on the fly in nfsd4_decode_compound(). Other than code
> recently fixed by 01529e3f8179 "NFSD: Fix memory leak in encoding
> denied
> lock", I don't know of any examples of code depending on this
> initialization. But it definitely seems possible, and I'd rather be
> safe.
>
> Compounds this long are unusual so I'm much more worried about failure
> in this poorly tested cases than about an insignificant performance
> hit.
>
> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
>
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 01023a5..628b430 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -1635,7 +1635,7 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
> goto xdr_error;
>
> if (argp->opcnt > ARRAY_SIZE(argp->iops)) {
> - argp->ops = kmalloc(argp->opcnt * sizeof(*argp->ops),
> GFP_KERNEL);
> + argp->ops = kzalloc(argp->opcnt * sizeof(*argp->ops),
> GFP_KERNEL);
> if (!argp->ops) {
> argp->ops = argp->iops;
> dprintk("nfsd: couldn't allocate room for
> COMPOUND\n");
>
> Thanks,
> Junxiao.
> >
>
Yes, that patch looks fine, and I'm pretty sure it'd be ok for stable.
I don't think v3.8 is being maintained anymore though, is it?
--
Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
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