From cee7cefc610d42fd383b3c80c12cbc675443176a Mon Sep 17 00:00:00 2001
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From: Robin Watts <Robin.Watts@artifex.com>
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Date: Fri, 22 Jan 2021 17:05:15 +0000
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Subject: [PATCH] Bug 703366: Fix double free of object during linearization.
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This appears to happen because we parse an illegal object from
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a broken file and assign it to object 0, which is defined to
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be free.
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Here, we fix the parsing code so this can't happen.
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[Retrieved from:
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http://git.ghostscript.com/?p=mupdf.git;h=cee7cefc610d42fd383b3c80c12cbc675443176a]
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Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
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---
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source/pdf/pdf-parse.c | 6 ++++++
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source/pdf/pdf-xref.c | 2 ++
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2 files changed, 8 insertions(+)
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diff --git a/source/pdf/pdf-parse.c b/source/pdf/pdf-parse.c
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index 7abc8c3d4..5761c3351 100644
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--- a/source/pdf/pdf-parse.c
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+++ b/source/pdf/pdf-parse.c
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@@ -749,6 +749,12 @@ pdf_parse_ind_obj(fz_context *ctx, pdf_document *doc,
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fz_throw(ctx, FZ_ERROR_SYNTAX, "expected generation number (%d ? obj)", num);
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}
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gen = buf->i;
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+ if (gen < 0 || gen >= 65536)
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+ {
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+ if (try_repair)
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+ *try_repair = 1;
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+ fz_throw(ctx, FZ_ERROR_SYNTAX, "invalid generation number (%d)", gen);
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+ }
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tok = pdf_lex(ctx, file, buf);
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if (tok != PDF_TOK_OBJ)
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diff --git a/source/pdf/pdf-xref.c b/source/pdf/pdf-xref.c
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index 1b2bdcd59..30197b4b8 100644
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--- a/source/pdf/pdf-xref.c
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+++ b/source/pdf/pdf-xref.c
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@@ -1190,6 +1190,8 @@ pdf_read_new_xref(fz_context *ctx, pdf_document *doc, pdf_lexbuf *buf)
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{
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ofs = fz_tell(ctx, doc->file);
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trailer = pdf_parse_ind_obj(ctx, doc, doc->file, buf, &num, &gen, &stm_ofs, NULL);
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+ if (num == 0)
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+ fz_throw(ctx, FZ_ERROR_GENERIC, "Trailer object number cannot be 0\n");
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}
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fz_catch(ctx)
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{
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--
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2.17.1
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