linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Roman Kagan <rkagan@virtuozzo.com>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Matthew Wilcox" <mawilcox@microsoft.com>,
	syzbot <syzbot+35666cba7f0a337e2e79@syzkaller.appspotmail.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"KVM list" <kvm@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"the arch/x86 maintainers" <x86@kernel.org>,
	"Cathy Avery" <cavery@redhat.com>,
	stable <stable@vger.kernel.org>
Subject: Re: [PATCH] idr: fix invalid ptr dereference on item delete
Date: Fri, 11 May 2018 08:57:04 +0300	[thread overview]
Message-ID: <20180511055704.GB12563@rkaganip.lan> (raw)
In-Reply-To: <CACT4Y+bZaW6NN-RdVd+EL1pXQs42Nb-dWUn733=eEORT_3NjUA@mail.gmail.com>

On Fri, May 11, 2018 at 07:40:26AM +0200, Dmitry Vyukov wrote:
> On Fri, May 11, 2018 at 1:54 AM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> > On 10/05/2018 21:16, Roman Kagan wrote:
> >> If an IDR contains a single entry at index==0, the underlying radix tree
> >> has a single item in its root node, in which case
> >> __radix_tree_lookup(index!=0) doesn't set its *@nodep argument (in
> >> addition to returning NULL).
> >>
> >> However, the tree itself is not empty, i.e. the tree root doesn't have
> >> IDR_FREE tag.
> >>
> >> As a result, on an attempt to remove an index!=0 entry from such an IDR,
> >> radix_tree_delete_item doesn't return early and calls
> >> __radix_tree_delete with invalid parameters which are then dereferenced.
> >>
> >> Reported-by: syzbot+35666cba7f0a337e2e79@syzkaller.appspotmail.com
> >> Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
> >> ---
> >>  lib/radix-tree.c | 5 +++--
> >>  1 file changed, 3 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/lib/radix-tree.c b/lib/radix-tree.c
> >> index da9e10c827df..10ff1bfae952 100644
> >> --- a/lib/radix-tree.c
> >> +++ b/lib/radix-tree.c
> >> @@ -2040,8 +2040,9 @@ void *radix_tree_delete_item(struct radix_tree_root *root,
> >>       void *entry;
> >>
> >>       entry = __radix_tree_lookup(root, index, &node, &slot);
> >> -     if (!entry && (!is_idr(root) || node_tag_get(root, node, IDR_FREE,
> >> -                                             get_slot_offset(node, slot))))
> >> +     if (!entry && (!is_idr(root) || !node ||
> >> +                    node_tag_get(root, node, IDR_FREE,
> >> +                                 get_slot_offset(node, slot))))
> >>               return NULL;
> >>
> >>       if (item && entry != item)
> >>
> >
> > I cannot really vouch for the patch, but if it is correct it's
> > definitely stuff for stable.  The KVM testcase is only for 4.17-rc but
> > this is a really nasty bug in a core data structure.
> >
> > Cc: stable@vger.kernel.org
> >
> > Should radix-tree be compilable in userspace, so that we can add unit
> > tests for it?...
> 
> Good point.
> 
> For my education, what/where are the tests that run as user-space code?

Actually there are userspace tests for it under tools/tests/radix-tree,
but I didn't manage to get them to build.  Looks like the recent
introduction of a spin_lock in the radix_tree structure (for XArray
work?) broke them.

Roman.

  reply	other threads:[~2018-05-11  5:57 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-10 19:16 Roman Kagan
2018-05-10 23:54 ` Paolo Bonzini
2018-05-11  5:40   ` Dmitry Vyukov
2018-05-11  5:57     ` Roman Kagan [this message]
2018-05-11  9:12       ` Paolo Bonzini
2018-05-18 20:29 ` Roman Kagan
2018-05-18 17:50 Matthew Wilcox
2018-05-18 20:23 ` Roman Kagan
2018-05-19  0:31   ` Matthew Wilcox
2018-05-18 22:31 ` Andrew Morton
2018-05-19  0:28   ` Matthew Wilcox
2018-05-19  6:26   ` Roman Kagan
2018-05-19 14:14     ` Matthew Wilcox
2018-05-21 19:13       ` Andrew Morton

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180511055704.GB12563@rkaganip.lan \
    --to=rkagan@virtuozzo.com \
    --cc=cavery@redhat.com \
    --cc=dvyukov@google.com \
    --cc=hpa@zytor.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mawilcox@microsoft.com \
    --cc=mingo@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=rkrcmar@redhat.com \
    --cc=stable@vger.kernel.org \
    --cc=syzbot+35666cba7f0a337e2e79@syzkaller.appspotmail.com \
    --cc=syzkaller-bugs@googlegroups.com \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    --subject='Re: [PATCH] idr: fix invalid ptr dereference on item delete' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
on how to clone and mirror all data and code used for this inbox