On Mon, Mar 31, 2025 at 02:43:34PM +0200, Florian Westphal wrote:
> After patch, this gets rejected with:
> internal:0:0-0: Error: conflicting protocols specified: ip vs ip6
>
> Without patch, we crash with a NULL dereference: we cannot use
> reject.expr->location unconditionally.
>
> Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Reviewed-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Thanks!
> ---
> src/evaluate.c | 16 ++++++++--
> .../reject_stmt_with_no_expression_crash | 32 +++++++++++++++++++
> 2 files changed, 46 insertions(+), 2 deletions(-)
> create mode 100644 tests/shell/testcases/bogons/nft-j-f/reject_stmt_with_no_expression_crash
>
> diff --git a/src/evaluate.c b/src/evaluate.c
> index 507b1c86cafc..e4a7b5ceaafa 100644
> --- a/src/evaluate.c
> +++ b/src/evaluate.c
> @@ -3791,6 +3791,18 @@ static int stmt_evaluate_reject_bridge(struct eval_ctx *ctx, struct stmt *stmt)
> return 0;
> }
>
> +static int stmt_reject_error(struct eval_ctx *ctx,
> + const struct stmt *stmt,
> + const char *msg)
> +{
> + struct expr *e = stmt->reject.expr;
> +
> + if (e)
> + return stmt_binary_error(ctx, e, stmt, "%s", msg);
> +
> + return stmt_error(ctx, stmt, "%s", msg);
> +}
> +
> static int stmt_evaluate_reject_family(struct eval_ctx *ctx, struct stmt *stmt)
> {
> struct proto_ctx *pctx = eval_proto_ctx(ctx);
> @@ -3806,12 +3818,12 @@ static int stmt_evaluate_reject_family(struct eval_ctx *ctx, struct stmt *stmt)
> return -1;
> break;
> case NFT_REJECT_ICMPX_UNREACH:
> - return stmt_binary_error(ctx, stmt->reject.expr, stmt,
> + return stmt_reject_error(ctx, stmt,
> "abstracted ICMP unreachable not supported");
> case NFT_REJECT_ICMP_UNREACH:
> if (stmt->reject.family == pctx->family)
> break;
> - return stmt_binary_error(ctx, stmt->reject.expr, stmt,
> + return stmt_reject_error(ctx, stmt,
> "conflicting protocols specified: ip vs ip6");
> }
> break;
> diff --git a/tests/shell/testcases/bogons/nft-j-f/reject_stmt_with_no_expression_crash b/tests/shell/testcases/bogons/nft-j-f/reject_stmt_with_no_expression_crash
> new file mode 100644
> index 000000000000..04c01aa77a29
> --- /dev/null
> +++ b/tests/shell/testcases/bogons/nft-j-f/reject_stmt_with_no_expression_crash
> @@ -0,0 +1,32 @@
> +{
> + "nftables": [
> + {
> + "table": { "family": "ip", "name": "x",
> + "handle": 0
> + }
> + },
> + {
> + "chain": {
> + "family": "ip",
> + "table": "x",
> + "name": "c",
> + "handle": 0
> + }
> + },
> + {
> + "rule": {
> + "family": "ip",
> + "table": "x",
> + "chain": "c",
> + "expr": [
> + {
> + "reject": {
> + "type": "icmpv6",
> + "exprlimit": "port-unreachable"
> + }
> + }
> + ]
> + }
> + }
> + ]
> +}
> --
> 2.49.0
>
>
