From c3f9a7caecbf5239f29b6fd1a7edf47df4fc6d21 Mon Sep 17 00:00:00 2001 From: John MacFarlane Date: Sun, 26 Oct 2014 11:57:43 -0700 Subject: 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. --- src/inlines.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'src/inlines.c') diff --git a/src/inlines.c b/src/inlines.c index 7a7f08a..928a3ac 100644 --- 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; -- cgit v1.2.3 From adc78c85809fb2f79f967d29713e2d9f520aea5b Mon Sep 17 00:00:00 2001 From: John MacFarlane Date: Tue, 28 Oct 2014 22:21:45 -0700 Subject: Rename number_of_emphasis_openers -> emphasis_nestlevel. --- src/inlines.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'src/inlines.c') diff --git a/src/inlines.c b/src/inlines.c index 928a3ac..d282170 100644 --- a/src/inlines.c +++ b/src/inlines.c @@ -23,7 +23,7 @@ typedef struct Subject { int label_nestlevel; reference_map *refmap; inline_stack *emphasis_openers; - int number_of_emphasis_openers; + int emphasis_nestlevel; } subject; static node_inl *parse_chunk_inlines(chunk *chunk, reference_map *refmap); @@ -178,7 +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; + e->emphasis_nestlevel = 0; chunk_rtrim(&e->input); } @@ -192,7 +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; + e->emphasis_nestlevel = 0; chunk_rtrim(&e->input); } @@ -312,7 +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--; + subj->emphasis_nestlevel--; free(tempstack); } } @@ -393,7 +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 && subj->number_of_emphasis_openers < EMPHASIS_STACK_LIMIT) + if (can_open && subj->emphasis_nestlevel < EMPHASIS_STACK_LIMIT) { istack = (inline_stack*)malloc(sizeof(inline_stack)); if (istack == NULL) { @@ -404,7 +404,7 @@ cannotClose: istack->first_inline = inl_text; istack->previous = subj->emphasis_openers; subj->emphasis_openers = istack; - subj->number_of_emphasis_openers++; + subj->emphasis_nestlevel++; } return inl_text; -- cgit v1.2.3 From 9253c0eab573e5ca0d37e4b1db77d3b0bfcf3be6 Mon Sep 17 00:00:00 2001 From: John MacFarlane Date: Tue, 28 Oct 2014 22:57:01 -0700 Subject: Changed EMPHASIS_STACK_LIMIT -> STACK_LIMIT. We'll also use it in parsing bracketed link labels. --- src/inlines.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src/inlines.c') diff --git a/src/inlines.c b/src/inlines.c index d282170..26eb02a 100644 --- a/src/inlines.c +++ b/src/inlines.c @@ -393,7 +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 && subj->emphasis_nestlevel < EMPHASIS_STACK_LIMIT) + if (can_open && subj->emphasis_nestlevel < STACK_LIMIT) { istack = (inline_stack*)malloc(sizeof(inline_stack)); if (istack == NULL) { -- cgit v1.2.3 From 67619a5d5c71c44565a9a0413aaf78f9baece528 Mon Sep 17 00:00:00 2001 From: John MacFarlane Date: Tue, 28 Oct 2014 23:03:02 -0700 Subject: Disallow bracketed labels nested more than 1000 deep. For performance reasons. See #166. --- src/inlines.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'src/inlines.c') diff --git a/src/inlines.c b/src/inlines.c index 26eb02a..9216979 100644 --- a/src/inlines.c +++ b/src/inlines.c @@ -594,7 +594,8 @@ static int link_label(subject* subj, chunk *raw_label) advance(subj); // advance past [ unsigned char c; - while ((c = peek_char(subj)) && (c != ']' || nestlevel > 0)) { + while ((c = peek_char(subj)) && + (c != ']' || (nestlevel > 0 && nestlevel < STACK_LIMIT))) { switch (c) { case '`': tmp = handle_backticks(subj); @@ -622,7 +623,7 @@ static int link_label(subject* subj, chunk *raw_label) advance(subj); } } - if (c == ']') { + if (nestlevel == 0 && c == ']') { *raw_label = chunk_dup(&subj->input, startpos + 1, subj->pos - (startpos + 1)); subj->label_nestlevel = 0; advance(subj); // advance past ] -- cgit v1.2.3