My personal build of CMark ✏️
Add EMPHASIS_STACK_LIMIT.
If we get more than 1000 deep in potential emphasis/strong emphasis openers, we refuse to add more to the stack. This prevents the sort of stack overflow we previously got with
python -c 'print "*a **a " * 100000; print " a** a*" * 100000' | ./cmark
Partially addresses #166.
2 files changed, 7 insertions, 1 deletion
| Status | File Name | N° Changes | Insertions | Deletions |
| Modified | src/cmark.h | 1 | 1 | 0 |
| Modified | src/inlines.c | 7 | 6 | 1 |
diff --git a/src/cmark.h b/src/cmark.h @@ -9,6 +9,7 @@ #define VERSION "0.1" #define CODE_INDENT 4 +#define EMPHASIS_STACK_LIMIT 1000 struct node_inl { enum {
diff --git a/src/inlines.c b/src/inlines.c @@ -23,6 +23,7 @@ typedef struct Subject { int label_nestlevel; reference_map *refmap; inline_stack *emphasis_openers; + int number_of_emphasis_openers; } subject; static node_inl *parse_chunk_inlines(chunk *chunk, reference_map *refmap); @@ -177,6 +178,7 @@ static void subject_from_buf(subject *e, strbuf *buffer, reference_map *refmap) e->label_nestlevel = 0; e->refmap = refmap; e->emphasis_openers = NULL; + e->number_of_emphasis_openers = 0; chunk_rtrim(&e->input); } @@ -190,6 +192,7 @@ static void subject_from_chunk(subject *e, chunk *chunk, reference_map *refmap) e->label_nestlevel = 0; e->refmap = refmap; e->emphasis_openers = NULL; + e->number_of_emphasis_openers = 0; chunk_rtrim(&e->input); } @@ -309,6 +312,7 @@ static void free_openers(subject* subj, inline_stack* istack) while (subj->emphasis_openers != istack) { tempstack = subj->emphasis_openers; subj->emphasis_openers = subj->emphasis_openers->previous; + subj->number_of_emphasis_openers--; free(tempstack); } } @@ -389,7 +393,7 @@ static node_inl* handle_strong_emph(subject* subj, unsigned char c, node_inl **l cannotClose: inl_text = make_str(chunk_dup(&subj->input, subj->pos - numdelims, numdelims)); - if (can_open) + if (can_open && subj->number_of_emphasis_openers < EMPHASIS_STACK_LIMIT) { istack = (inline_stack*)malloc(sizeof(inline_stack)); if (istack == NULL) { @@ -400,6 +404,7 @@ cannotClose: istack->first_inline = inl_text; istack->previous = subj->emphasis_openers; subj->emphasis_openers = istack; + subj->number_of_emphasis_openers++; } return inl_text;