From: Roman Kagan <rkagan@virtuozzo.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Matthew Wilcox <mawilcox@microsoft.com>
Cc: syzbot+35666cba7f0a337e2e79@syzkaller.appspotmail.com,
hpa@zytor.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
mingo@redhat.com, rkrcmar@redhat.com,
syzkaller-bugs@googlegroups.com, tglx@linutronix.de,
x86@kernel.org, Cathy Avery <cavery@redhat.com>
Subject: [PATCH] idr: fix invalid ptr dereference on item delete
Date: Thu, 10 May 2018 22:16:34 +0300 [thread overview]
Message-ID: <20180510191634.18796-1-rkagan@virtuozzo.com> (raw)
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)
--
2.17.0
next reply other threads:[~2018-05-10 19:17 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-10 19:16 Roman Kagan [this message]
2018-05-10 23:54 ` [PATCH] idr: fix invalid ptr dereference on item delete Paolo Bonzini
2018-05-11 5:40 ` Dmitry Vyukov
2018-05-11 5:57 ` Roman Kagan
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=20180510191634.18796-1-rkagan@virtuozzo.com \
--to=rkagan@virtuozzo.com \
--cc=cavery@redhat.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=syzbot+35666cba7f0a337e2e79@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).