scanner: incorrect error reporting after file inclusion

scanner_pop_buffer() incorrectly sets the current input descriptor. The
state->indesc_idx field actually stores the number of input descriptors
in the stack, decrement it and then update the current input descriptor
accordingly.

Fixes: 60e917fa7cb5 ("src: dynamic input_descriptor allocation")
Closes: https://bugzilla.netfilter.org/show_bug.cgi?id=1383
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/src/scanner.l b/src/scanner.l
index 4fbdcf2afa4b8bc52cf0cf276b148d49562ced0f..99ee83559d2eb274def5179beb1bc1308f2c02a9 100644 (file)
--- a/src/scanner.l
+++ b/src/scanner.l
@@ -665,12 +665,29 @@ addrstring        ({macaddr}|{ip4addr}|{ip6addr})
 
 %%
 
+static void scanner_push_indesc(struct parser_state *state,
+                               struct input_descriptor *indesc)
+{
+       state->indescs[state->indesc_idx] = indesc;
+       state->indesc = state->indescs[state->indesc_idx++];
+}
+
+static void scanner_pop_indesc(struct parser_state *state)
+{
+       state->indesc_idx--;
+
+       if (state->indesc_idx > 0)
+               state->indesc = state->indescs[state->indesc_idx - 1];
+       else
+               state->indesc = NULL;
+}
+
 static void scanner_pop_buffer(yyscan_t scanner)
 {
        struct parser_state *state = yyget_extra(scanner);
 
        yypop_buffer_state(scanner);
-       state->indesc = state->indescs[--state->indesc_idx];
+       scanner_pop_indesc(state);
 }
 
 static void scanner_push_file(struct nft_ctx *nft, void *scanner,
@@ -691,8 +708,7 @@ static void scanner_push_file(struct nft_ctx *nft, void *scanner,
        indesc->name    = xstrdup(filename);
        init_pos(indesc);
 
-       state->indescs[state->indesc_idx] = indesc;
-       state->indesc = state->indescs[state->indesc_idx++];
+       scanner_push_indesc(state, indesc);
        list_add_tail(&indesc->list, &state->indesc_list);
 }