From: Florian Westphal <fw@xxxxxxxxx>
commit fd94d9dadee58e09b49075240fe83423eb1dcd36 upstream.
If priv->len is a multiple of 4, then dst[len / 4] can write past
the destination array which leads to stack corruption.
This construct is necessary to clean the remainder of the register
in case ->len is NOT a multiple of the register size, so make it
conditional just like nft_payload.c does.
The bug was added in 4.1 cycle and then copied/inherited when
tcp/sctp and ip option support was added.
Bug reported by Zero Day Initiative project (ZDI-CAN-21950,
ZDI-CAN-21951, ZDI-CAN-21961).
Fixes: 49499c3e6e18 ("netfilter: nf_tables: switch registers to 32 bit addressing")
Fixes: 935b7f643018 ("netfilter: nft_exthdr: add TCP option matching")
Fixes: 133dc203d77d ("netfilter: nft_exthdr: Support SCTP chunks")
Fixes: dbb5281a1f84 ("netfilter: nf_tables: add support for matching IPv4 options")
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/netfilter/nft_exthdr.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -36,6 +36,14 @@ static unsigned int optlen(const u8 *opt
return opt[offset + 1];
}
+static int nft_skb_copy_to_reg(const struct sk_buff *skb, int offset, u32 *dest, unsigned int len)
+{
+ if (len % NFT_REG32_SIZE)
+ dest[len / NFT_REG32_SIZE] = 0;
+
+ return skb_copy_bits(skb, offset, dest, len);
+}
+
static void nft_exthdr_ipv6_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
@@ -57,8 +65,7 @@ static void nft_exthdr_ipv6_eval(const s
}
offset += priv->offset;
- dest[priv->len / NFT_REG32_SIZE] = 0;
- if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0)
+ if (nft_skb_copy_to_reg(pkt->skb, offset, dest, priv->len) < 0)
goto err;
return;
err:
@@ -114,7 +121,8 @@ static void nft_exthdr_tcp_eval(const st
if (priv->flags & NFT_EXTHDR_F_PRESENT) {
*dest = 1;
} else {
- dest[priv->len / NFT_REG32_SIZE] = 0;
+ if (priv->len % NFT_REG32_SIZE)
+ dest[priv->len / NFT_REG32_SIZE] = 0;
memcpy(dest, opt + offset, priv->len);
}
Patches currently in stable-queue which might be from kroah.com@xxxxxxxxxxxxxxx are
queue-4.19/netfilter-nf_tables-bogus-ebusy-when-deleting-flowtable-after-flush-for-4.19.patch
queue-4.19/netfilter-nft_set_rbtree-switch-to-node-list-walk-for-overlap-detection.patch
queue-4.19/netfilter-nf_tables-validate-nfproto_-family.patch
queue-4.19/netfilter-nf_tables-unregister-flowtable-hooks-on-netns-exit.patch
queue-4.19/netfilter-nf_tables-fix-gc-transaction-races-with-netns-and-netlink-event-exit-path.patch
queue-4.19/netfilter-nft_set_rbtree-use-read-spinlock-to-avoid-datapath-contention.patch
queue-4.19/netfilter-nft_dynset-report-eopnotsupp-on-missing-set-feature.patch
queue-4.19/netfilter-nf_tables-discard-table-flag-update-with-pending-basechain-deletion.patch
queue-4.19/netfilter-nft_set_rbtree-skip-sync-gc-for-new-elements-in-this-transaction.patch
queue-4.19/netfilter-nf_tables-mark-set-as-dead-when-unbinding-anonymous-set-with-timeout.patch
queue-4.19/netfilter-nf_tables-reject-new-basechain-after-table-flag-update.patch
queue-4.19/netfilter-nf_tables-gc-transaction-race-with-netns-dismantle.patch
queue-4.19/netfilter-nftables-update-table-flags-from-the-commit-phase.patch
queue-4.19/netfilter-nf_tables-allow-nfproto_inet-in-nft_-match-target-_validate.patch
queue-4.19/netfilter-nft_set_rbtree-skip-end-interval-element-from-gc.patch
queue-4.19/netfilter-nf_tables-drop-map-element-references-from-preparation-phase.patch
queue-4.19/netfilter-nf_tables-gc-transaction-race-with-abort-path.patch
queue-4.19/netfilter-nf_tables-fix-memleak-when-more-than-255-elements-expired.patch
queue-4.19/netfilter-nft_set_rbtree-add-missing-expired-checks.patch
queue-4.19/netfilter-nf_tables-double-hook-unregistration-in-netns-path.patch
queue-4.19/netfilter-nft_dynset-relax-superfluous-check-on-set-updates.patch
queue-4.19/netfilter-nf_tables-defer-gc-run-if-previous-batch-is-still-pending.patch
queue-4.19/netfilter-nft_set_hash-try-later-when-gc-hits-eagain-on-iteration.patch
queue-4.19/netfilter-nft_dynset-fix-timeouts-later-than-23-days.patch
queue-4.19/netfilter-nf_tables-mark-newset-as-dead-on-transaction-abort.patch
queue-4.19/netfilter-nf_tables-don-t-skip-expired-elements-during-walk.patch
queue-4.19/netfilter-nftables-rename-set-element-data-activation-deactivation-functions.patch
queue-4.19/netfilter-nf_tables-gc-transaction-api-to-avoid-race-with-control-plane.patch
queue-4.19/netfilter-nf_tables-set-dormant-flag-on-hook-register-failure.patch
queue-4.19/netfilter-nf_tables-remove-busy-mark-and-gc-batch-api.patch
queue-4.19/netfilter-nf_tables-skip-dead-set-elements-in-netlink-dump.patch
queue-4.19/netfilter-nf_tables-adapt-set-backend-to-use-gc-transaction-api.patch
queue-4.19/netfilter-nft_set_rbtree-fix-overlap-expiration-walk.patch
queue-4.19/netfilter-nf_tables-fix-table-flag-updates.patch
queue-4.19/netfilter-nf_tables-do-not-compare-internal-table-flags-on-updates.patch
queue-4.19/netfilter-nft_set_rbtree-allow-loose-matching-of-closing-element-in-interval.patch
queue-4.19/netfilter-nftables-exthdr-fix-4-byte-stack-oob-write.patch
queue-4.19/netfilter-nft_set_rbtree-fix-null-deref-on-element-insertion.patch
queue-4.19/netfilter-nf_tables-pass-context-to-nft_set_destroy.patch
queue-4.19/netfilter-nf_tables-disable-toggling-dormant-table-state-more-than-once.patch
