Bug 699694: Fix reference counting for JBIG2 globals.

fz_open_jbig2d() is called at two locations in MuPDF. At one
location a reference to the JBIG2 globals struct was taken before
passing it to fz_open_jbig2d(). At the other location no such
reference was taken, but rather ownership of the struct was
implicitly transferred to fz_open_jbig2d(). This inconsistency
led to a leak of the globals struct at the first location.

Now, passing a JBIG2 globals struct to fz_open_jbig2d() never
implictly takes ownership. Instead the JBIG2 stream will take a
reference if it needs it and drops it in case of error. As usual
it is the callers responsibility to drop the reference to the
globals struct it owns.

3 files changed, 26 insertions, 34 deletions

diff --git a/source/fitz/compressed-buffer.c b/source/fitz/compressed-buffer.c
index 35b0868b..9a4f5c23 100644
--- a/source/fitz/compressed-buffer.c
+++ b/source/fitz/compressed-buffer.c
@@ -69,7 +69,7 @@ fz_open_image_decomp_stream(fz_context *ctx, fz_stream *tail, fz_compression_par
 			break;
 
 		case FZ_IMAGE_JBIG2:
-			head = fz_open_jbig2d(ctx, tail, fz_keep_jbig2_globals(ctx, params->u.jbig2.globals));
+			head = fz_open_jbig2d(ctx, tail, params->u.jbig2.globals);
 			break;
 
 		case FZ_IMAGE_RLD:
diff --git a/source/fitz/filter-jbig2.c b/source/fitz/filter-jbig2.c
index e984b6cf..7fadc02b 100644
--- a/source/fitz/filter-jbig2.c
+++ b/source/fitz/filter-jbig2.c
@@ -226,16 +226,9 @@ fz_open_jbig2d(fz_context *ctx, fz_stream *chain, fz_jbig2_globals *globals)
 {
 	fz_jbig2d *state = NULL;
 
-	fz_try(ctx)
-		state = fz_malloc_struct(ctx, fz_jbig2d);
-	fz_catch(ctx)
-	{
-		fz_drop_jbig2_globals(ctx, globals);
-		fz_rethrow(ctx);
-	}
-
+	state = fz_malloc_struct(ctx, fz_jbig2d);
 	state->ctx = ctx;
-	state->gctx = globals;
+	state->gctx = fz_keep_jbig2_globals(ctx, globals);
 	state->chain = fz_keep_stream(ctx, chain);
 	state->idx = 0;
 	state->output = NULL;
@@ -416,30 +409,16 @@ fz_open_jbig2d(fz_context *ctx, fz_stream *chain, fz_jbig2_globals *globals)
 
 	fz_var(state);
 
-	fz_try(ctx)
-	{
-		state = fz_malloc_struct(ctx, fz_jbig2d);
-		state->gctx = globals;
-		state->alloc.ctx = ctx;
-		state->alloc.alloc.alloc = fz_jbig2_alloc;
-		state->alloc.alloc.free = fz_jbig2_free;
-		state->alloc.alloc.realloc = fz_jbig2_realloc;
-		state->ctx = jbig2_ctx_new((Jbig2Allocator *) &state->alloc, JBIG2_OPTIONS_EMBEDDED, globals ? globals->gctx : NULL, error_callback, ctx);
-		state->page = NULL;
-		state->idx = 0;
-		state->chain = fz_keep_stream(ctx, chain);
-	}
-	fz_catch(ctx)
-	{
-		if (state)
-		{
-			fz_drop_jbig2_globals(ctx, state->gctx);
-			if (state->ctx)
-				jbig2_ctx_free(state->ctx);
-		}
-		fz_free(ctx, state);
-		fz_rethrow(ctx);
-	}
+	state = fz_malloc_struct(ctx, fz_jbig2d);
+	state->gctx = fz_keep_jbig2_globals(ctx, globals);
+	state->alloc.ctx = ctx;
+	state->alloc.alloc.alloc = fz_jbig2_alloc;
+	state->alloc.alloc.free = fz_jbig2_free;
+	state->alloc.alloc.realloc = fz_jbig2_realloc;
+	state->ctx = jbig2_ctx_new((Jbig2Allocator *) &state->alloc, JBIG2_OPTIONS_EMBEDDED, globals ? globals->gctx : NULL, error_callback, ctx);
+	state->page = NULL;
+	state->idx = 0;
+	state->chain = fz_keep_stream(ctx, chain);
 
 	return fz_new_stream(ctx, state, next_jbig2d, close_jbig2d);
 }
diff --git a/source/pdf/pdf-stream.c b/source/pdf/pdf-stream.c
index f52539cf..29301f5d 100644
--- a/source/pdf/pdf-stream.c
+++ b/source/pdf/pdf-stream.c
@@ -173,6 +173,7 @@ build_filter(fz_context *ctx, fz_stream *chain, pdf_document *doc, pdf_obj *f, p
 {
 	fz_compression_params local_params;
 
+	local_params.u.jbig2.globals = NULL;
 	if (params == NULL)
 		params = &local_params;
 
@@ -184,6 +185,18 @@ build_filter(fz_context *ctx, fz_stream *chain, pdf_document *doc, pdf_obj *f, p
 	if (params != &local_params && params->type != FZ_IMAGE_RAW)
 		return fz_keep_stream(ctx, chain); /* nothing to do */
 
+	else if (params->type == FZ_IMAGE_JBIG2)
+	{
+		fz_stream *stm;
+		fz_try(ctx)
+			stm = fz_open_image_decomp_stream(ctx, chain, params, NULL);
+		fz_always(ctx)
+			fz_drop_jbig2_globals(ctx, local_params.u.jbig2.globals);
+		fz_catch(ctx)
+			fz_rethrow(ctx);
+		return stm;
+	}
+
 	else if (params->type != FZ_IMAGE_RAW)
 		return fz_open_image_decomp_stream(ctx, chain, params, NULL);