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filter: prevent nla extensions to peek beyond the end of the message (CVE-2014-3144, CVE-2014-3145) 

svn path=/dists/sid/linux/; revision=21326
This commit is contained in:
Ben Hutchings 2014-05-13 15:44:00 +00:00
parent d326c007c7
commit cf43c3a854
3 changed files with 81 additions and 0 deletions
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2
debian/changelog vendored
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@ -110,6 +110,8 @@ linux (3.14.4-1) UNRELEASED; urgency=medium
* drm: Enable auto-loading of ast, udl
* [ppc64el] Build a linux-libc-dev package (Closes: #747367)
* net: ipv4: current group_info should be put after using. (CVE-2014-2851)
* filter: prevent nla extensions to peek beyond the end of the message
(CVE-2014-3144, CVE-2014-3145)
-- Ben Hutchings <ben@decadent.org.uk> Thu, 01 May 2014 01:50:30 +0100

78
debian/patches/bugfix/all/filter-prevent-nla-extensions-to-peek-beyond-the-end.patch vendored Normal file
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@ -0,0 +1,78 @@
From: Mathias Krause <minipli@googlemail.com>
Date: Sun, 13 Apr 2014 18:23:33 +0200
Subject: filter: prevent nla extensions to peek beyond the end of the message
Origin: https://git.kernel.org/linus/05ab8f2647e4221cbdb3856dd7d32bd5407316b3
The BPF_S_ANC_NLATTR and BPF_S_ANC_NLATTR_NEST extensions fail to check
for a minimal message length before testing the supplied offset to be
within the bounds of the message. This allows the subtraction of the nla
header to underflow and therefore -- as the data type is unsigned --
allowing far to big offset and length values for the search of the
netlink attribute.
The remainder calculation for the BPF_S_ANC_NLATTR_NEST extension is
also wrong. It has the minuend and subtrahend mixed up, therefore
calculates a huge length value, allowing to overrun the end of the
message while looking for the netlink attribute.
The following three BPF snippets will trigger the bugs when attached to
a UNIX datagram socket and parsing a message with length 1, 2 or 3.
,-[ PoC for missing size check in BPF_S_ANC_NLATTR ]--
| ld #0x87654321
| ldx #42
| ld #nla
| ret a
`---
,-[ PoC for the same bug in BPF_S_ANC_NLATTR_NEST ]--
| ld #0x87654321
| ldx #42
| ld #nlan
| ret a
`---
,-[ PoC for wrong remainder calculation in BPF_S_ANC_NLATTR_NEST ]--
| ; (needs a fake netlink header at offset 0)
| ld #0
| ldx #42
| ld #nlan
| ret a
`---
Fix the first issue by ensuring the message length fulfills the minimal
size constrains of a nla header. Fix the second bug by getting the math
for the remainder calculation right.
Fixes: 4738c1db15 ("[SKFILTER]: Add SKF_ADF_NLATTR instruction")
Fixes: d214c7537b ("filter: add SKF_AD_NLATTR_NEST to look for nested..")
Cc: Patrick McHardy <kaber@trash.net>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.14: This code is all in sk_run_filter(), not
separate functions]
---
net/core/filter.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -371,11 +371,15 @@ load_b:
if (skb_is_nonlinear(skb))
return 0;
+ if (skb->len < sizeof(struct nlattr))
+ return 0;
+ if (skb->len < sizeof(struct nlattr))
+ return 0;
if (A > skb->len - sizeof(struct nlattr))
return 0;
nla = (struct nlattr *)&skb->data[A];
- if (nla->nla_len > A - skb->len)
+ if (nla->nla_len > skb->len - A)
return 0;
nla = nla_find_nested(nla, X);

1
debian/patches/series vendored
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@ -83,3 +83,4 @@ features/arm/ARM-sun4i-dt-Add-bindings-for-USB-clocks.patch
features/arm/ARM-sun4i-dt-Add-USB-host-bindings.patch
bugfix/all/net-Start-with-correct-mac_len-in-skb_network_protoc.patch
bugfix/all/net-ipv4-current-group_info-should-be-put-after-usin.patch
bugfix/all/filter-prevent-nla-extensions-to-peek-beyond-the-end.patch