mirror of
https://github.com/Divested-Mobile/DivestOS-Build.git
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77 lines
3.5 KiB
Diff
77 lines
3.5 KiB
Diff
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From c58d6c93680f28ac58984af61d0a7ebf4319c241 Mon Sep 17 00:00:00 2001
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From: Phil Turnbull <phil.turnbull@oracle.com>
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Date: Tue, 2 Feb 2016 13:36:45 -0500
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Subject: netfilter: nfnetlink: correctly validate length of batch messages
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If nlh->nlmsg_len is zero then an infinite loop is triggered because
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'skb_pull(skb, msglen);' pulls zero bytes.
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The calculation in nlmsg_len() underflows if 'nlh->nlmsg_len <
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NLMSG_HDRLEN' which bypasses the length validation and will later
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trigger an out-of-bound read.
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If the length validation does fail then the malformed batch message is
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copied back to userspace. However, we cannot do this because the
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nlh->nlmsg_len can be invalid. This leads to an out-of-bounds read in
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netlink_ack:
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[ 41.455421] ==================================================================
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[ 41.456431] BUG: KASAN: slab-out-of-bounds in memcpy+0x1d/0x40 at addr ffff880119e79340
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[ 41.456431] Read of size 4294967280 by task a.out/987
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[ 41.456431] =============================================================================
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[ 41.456431] BUG kmalloc-512 (Not tainted): kasan: bad access detected
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[ 41.456431] -----------------------------------------------------------------------------
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...
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[ 41.456431] Bytes b4 ffff880119e79310: 00 00 00 00 d5 03 00 00 b0 fb fe ff 00 00 00 00 ................
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[ 41.456431] Object ffff880119e79320: 20 00 00 00 10 00 05 00 00 00 00 00 00 00 00 00 ...............
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[ 41.456431] Object ffff880119e79330: 14 00 0a 00 01 03 fc 40 45 56 11 22 33 10 00 05 .......@EV."3...
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[ 41.456431] Object ffff880119e79340: f0 ff ff ff 88 99 aa bb 00 14 00 0a 00 06 fe fb ................
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^^ start of batch nlmsg with
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nlmsg_len=4294967280
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...
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[ 41.456431] Memory state around the buggy address:
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[ 41.456431] ffff880119e79400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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[ 41.456431] ffff880119e79480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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[ 41.456431] >ffff880119e79500: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
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[ 41.456431] ^
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[ 41.456431] ffff880119e79580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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[ 41.456431] ffff880119e79600: fc fc fc fc fc fc fc fc fc fc fb fb fb fb fb fb
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[ 41.456431] ==================================================================
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Fix this with better validation of nlh->nlmsg_len and by setting
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NFNL_BATCH_FAILURE if any batch message fails length validation.
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CAP_NET_ADMIN is required to trigger the bugs.
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Fixes: 9ea2aa8b7dba ("netfilter: nfnetlink: validate nfnetlink header from batch")
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Signed-off-by: Phil Turnbull <phil.turnbull@oracle.com>
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Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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---
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net/netfilter/nfnetlink.c | 10 ++++++----
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1 file changed, 6 insertions(+), 4 deletions(-)
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diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
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index 62e92af..857ae89 100644
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--- a/net/netfilter/nfnetlink.c
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+++ b/net/netfilter/nfnetlink.c
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@@ -328,10 +328,12 @@ replay:
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nlh = nlmsg_hdr(skb);
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err = 0;
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- if (nlmsg_len(nlh) < sizeof(struct nfgenmsg) ||
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- skb->len < nlh->nlmsg_len) {
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- err = -EINVAL;
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- goto ack;
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+ if (nlh->nlmsg_len < NLMSG_HDRLEN ||
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+ skb->len < nlh->nlmsg_len ||
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+ nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
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+ nfnl_err_reset(&err_list);
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+ status |= NFNL_BATCH_FAILURE;
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+ goto done;
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}
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/* Only requests are handled by the kernel */
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--
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cgit v1.1
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