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-rw-r--r--gnu/packages/patches/libtiff-CVE-2017-9935.patch162
1 files changed, 162 insertions, 0 deletions
diff --git a/gnu/packages/patches/libtiff-CVE-2017-9935.patch b/gnu/packages/patches/libtiff-CVE-2017-9935.patch
new file mode 100644
index 0000000000..5685d81f68
--- /dev/null
+++ b/gnu/packages/patches/libtiff-CVE-2017-9935.patch
@@ -0,0 +1,162 @@
+Fix CVE-2017-9935
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-9935
+http://bugzilla.maptools.org/show_bug.cgi?id=2704
+
+Patch copied from upstream source repository:
+
+https://gitlab.com/libtiff/libtiff/commit/3dd8f6a357981a4090f126ab9025056c938b6940
+
+From 3dd8f6a357981a4090f126ab9025056c938b6940 Mon Sep 17 00:00:00 2001
+From: Brian May <brian@linuxpenguins.xyz>
+Date: Thu, 7 Dec 2017 07:46:47 +1100
+Subject: [PATCH] tiff2pdf: Fix CVE-2017-9935
+
+Fix for http://bugzilla.maptools.org/show_bug.cgi?id=2704
+
+This vulnerability - at least for the supplied test case - is because we
+assume that a tiff will only have one transfer function that is the same
+for all pages. This is not required by the TIFF standards.
+
+We than read the transfer function for every page. Depending on the
+transfer function, we allocate either 2 or 4 bytes to the XREF buffer.
+We allocate this memory after we read in the transfer function for the
+page.
+
+For the first exploit - POC1, this file has 3 pages. For the first page
+we allocate 2 extra extra XREF entries. Then for the next page 2 more
+entries. Then for the last page the transfer function changes and we
+allocate 4 more entries.
+
+When we read the file into memory, we assume we have 4 bytes extra for
+each and every page (as per the last transfer function we read). Which
+is not correct, we only have 2 bytes extra for the first 2 pages. As a
+result, we end up writing past the end of the buffer.
+
+There are also some related issues that this also fixes. For example,
+TIFFGetField can return uninitalized pointer values, and the logic to
+detect a N=3 vs N=1 transfer function seemed rather strange.
+
+It is also strange that we declare the transfer functions to be of type
+float, when the standard says they are unsigned 16 bit values. This is
+fixed in another patch.
+
+This patch will check to ensure that the N value for every transfer
+function is the same for every page. If this changes, we abort with an
+error. In theory, we should perhaps check that the transfer function
+itself is identical for every page, however we don't do that due to the
+confusion of the type of the data in the transfer function.
+---
+ libtiff/tif_dir.c | 3 +++
+ tools/tiff2pdf.c | 65 +++++++++++++++++++++++++++++++++++++------------------
+ 2 files changed, 47 insertions(+), 21 deletions(-)
+
+diff --git a/libtiff/tif_dir.c b/libtiff/tif_dir.c
+index 2ccaf448..cbf2b693 100644
+--- a/libtiff/tif_dir.c
++++ b/libtiff/tif_dir.c
+@@ -1065,6 +1065,9 @@ _TIFFVGetField(TIFF* tif, uint32 tag, va_list ap)
+ if (td->td_samplesperpixel - td->td_extrasamples > 1) {
+ *va_arg(ap, uint16**) = td->td_transferfunction[1];
+ *va_arg(ap, uint16**) = td->td_transferfunction[2];
++ } else {
++ *va_arg(ap, uint16**) = NULL;
++ *va_arg(ap, uint16**) = NULL;
+ }
+ break;
+ case TIFFTAG_REFERENCEBLACKWHITE:
+diff --git a/tools/tiff2pdf.c b/tools/tiff2pdf.c
+index d1a9b095..c3ec0746 100644
+--- a/tools/tiff2pdf.c
++++ b/tools/tiff2pdf.c
+@@ -1047,6 +1047,8 @@ void t2p_read_tiff_init(T2P* t2p, TIFF* input){
+ uint16 pagen=0;
+ uint16 paged=0;
+ uint16 xuint16=0;
++ uint16 tiff_transferfunctioncount=0;
++ float* tiff_transferfunction[3];
+
+ directorycount=TIFFNumberOfDirectories(input);
+ t2p->tiff_pages = (T2P_PAGE*) _TIFFmalloc(TIFFSafeMultiply(tmsize_t,directorycount,sizeof(T2P_PAGE)));
+@@ -1147,26 +1149,48 @@ void t2p_read_tiff_init(T2P* t2p, TIFF* input){
+ }
+ #endif
+ if (TIFFGetField(input, TIFFTAG_TRANSFERFUNCTION,
+- &(t2p->tiff_transferfunction[0]),
+- &(t2p->tiff_transferfunction[1]),
+- &(t2p->tiff_transferfunction[2]))) {
+- if((t2p->tiff_transferfunction[1] != (float*) NULL) &&
+- (t2p->tiff_transferfunction[2] != (float*) NULL) &&
+- (t2p->tiff_transferfunction[1] !=
+- t2p->tiff_transferfunction[0])) {
+- t2p->tiff_transferfunctioncount = 3;
+- t2p->tiff_pages[i].page_extra += 4;
+- t2p->pdf_xrefcount += 4;
+- } else {
+- t2p->tiff_transferfunctioncount = 1;
+- t2p->tiff_pages[i].page_extra += 2;
+- t2p->pdf_xrefcount += 2;
+- }
+- if(t2p->pdf_minorversion < 2)
+- t2p->pdf_minorversion = 2;
++ &(tiff_transferfunction[0]),
++ &(tiff_transferfunction[1]),
++ &(tiff_transferfunction[2]))) {
++
++ if((tiff_transferfunction[1] != (float*) NULL) &&
++ (tiff_transferfunction[2] != (float*) NULL)
++ ) {
++ tiff_transferfunctioncount=3;
++ } else {
++ tiff_transferfunctioncount=1;
++ }
+ } else {
+- t2p->tiff_transferfunctioncount=0;
++ tiff_transferfunctioncount=0;
+ }
++
++ if (i > 0){
++ if (tiff_transferfunctioncount != t2p->tiff_transferfunctioncount){
++ TIFFError(
++ TIFF2PDF_MODULE,
++ "Different transfer function on page %d",
++ i);
++ t2p->t2p_error = T2P_ERR_ERROR;
++ return;
++ }
++ }
++
++ t2p->tiff_transferfunctioncount = tiff_transferfunctioncount;
++ t2p->tiff_transferfunction[0] = tiff_transferfunction[0];
++ t2p->tiff_transferfunction[1] = tiff_transferfunction[1];
++ t2p->tiff_transferfunction[2] = tiff_transferfunction[2];
++ if(tiff_transferfunctioncount == 3){
++ t2p->tiff_pages[i].page_extra += 4;
++ t2p->pdf_xrefcount += 4;
++ if(t2p->pdf_minorversion < 2)
++ t2p->pdf_minorversion = 2;
++ } else if (tiff_transferfunctioncount == 1){
++ t2p->tiff_pages[i].page_extra += 2;
++ t2p->pdf_xrefcount += 2;
++ if(t2p->pdf_minorversion < 2)
++ t2p->pdf_minorversion = 2;
++ }
++
+ if( TIFFGetField(
+ input,
+ TIFFTAG_ICCPROFILE,
+@@ -1828,9 +1852,8 @@ void t2p_read_tiff_data(T2P* t2p, TIFF* input){
+ &(t2p->tiff_transferfunction[1]),
+ &(t2p->tiff_transferfunction[2]))) {
+ if((t2p->tiff_transferfunction[1] != (float*) NULL) &&
+- (t2p->tiff_transferfunction[2] != (float*) NULL) &&
+- (t2p->tiff_transferfunction[1] !=
+- t2p->tiff_transferfunction[0])) {
++ (t2p->tiff_transferfunction[2] != (float*) NULL)
++ ) {
+ t2p->tiff_transferfunctioncount=3;
+ } else {
+ t2p->tiff_transferfunctioncount=1;
+--
+2.16.1
+
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