netfilter: ebtables: CONFIG_COMPAT: don't trust userland offsets
commit b718121685
upstream.
We need to make sure the offsets are not out of range of the
total size.
Also check that they are in ascending order.
The WARN_ON triggered by syzkaller (it sets panic_on_warn) is
changed to also bail out, no point in continuing parsing.
Briefly tested with simple ruleset of
-A INPUT --limit 1/s' --log
plus jump to custom chains using 32bit ebtables binary.
Reported-by: <syzbot+845a53d13171abf8bf29@syzkaller.appspotmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
parent
c89e04e5c0
commit
eaa06bfba8
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@ -2053,7 +2053,9 @@ static int ebt_size_mwt(struct compat_ebt_entry_mwt *match32,
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if (match_kern)
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match_kern->match_size = ret;
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WARN_ON(type == EBT_COMPAT_TARGET && size_left);
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if (WARN_ON(type == EBT_COMPAT_TARGET && size_left))
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return -EINVAL;
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match32 = (struct compat_ebt_entry_mwt *) buf;
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}
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@ -2109,6 +2111,15 @@ static int size_entry_mwt(struct ebt_entry *entry, const unsigned char *base,
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*
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* offsets are relative to beginning of struct ebt_entry (i.e., 0).
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*/
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for (i = 0; i < 4 ; ++i) {
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if (offsets[i] >= *total)
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return -EINVAL;
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if (i == 0)
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continue;
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if (offsets[i-1] > offsets[i])
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return -EINVAL;
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}
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for (i = 0, j = 1 ; j < 4 ; j++, i++) {
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struct compat_ebt_entry_mwt *match32;
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unsigned int size;
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