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Fix buffer overflow in SGI-RLE decoding #4504

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merged 4 commits into from Apr 1, 2020
Merged

Fix buffer overflow in SGI-RLE decoding #4504

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394d6a1
Track number of pixels, not the number of runs
wiredfool Mar 28, 2020
dd341f1
Tests for SGI Overruns
wiredfool Mar 28, 2020
78478df
Black and isort
hugovk Apr 1, 2020
44096ad
Convert from unittest to pytest
hugovk Apr 1, 2020
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Binary file added Tests/images/sgi_crash.bin
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Binary file added Tests/images/sgi_overrun_expandrowF04.bin
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14 changes: 14 additions & 0 deletions Tests/test_sgi_crash.py
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@@ -0,0 +1,14 @@
#!/usr/bin/env python
import pytest
from PIL import Image


@pytest.mark.parametrize(
"test_file",
["Tests/images/sgi_overrun_expandrowF04.bin", "Tests/images/sgi_crash.bin"],
)
def test_crashes(test_file):
with open(test_file, "rb") as f:
im = Image.open(f)
with pytest.raises(IOError):
im.load()
8 changes: 6 additions & 2 deletions src/libImaging/SgiRleDecode.c
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Expand Up @@ -28,6 +28,7 @@ static void read4B(UINT32* dest, UINT8* buf)
static int expandrow(UINT8* dest, UINT8* src, int n, int z, int xsize)
{
UINT8 pixel, count;
int x = 0;

for (;n > 0; n--)
{
Expand All @@ -37,9 +38,10 @@ static int expandrow(UINT8* dest, UINT8* src, int n, int z, int xsize)
count = pixel & RLE_MAX_RUN;
if (!count)
return count;
if (count > xsize) {
if (x + count > xsize) {
return -1;
}
x += count;
if (pixel & RLE_COPY_FLAG) {
while(count--) {
*dest = *src++;
Expand All @@ -63,6 +65,7 @@ static int expandrow2(UINT8* dest, const UINT8* src, int n, int z, int xsize)
{
UINT8 pixel, count;

int x = 0;

for (;n > 0; n--)
{
Expand All @@ -73,9 +76,10 @@ static int expandrow2(UINT8* dest, const UINT8* src, int n, int z, int xsize)
count = pixel & RLE_MAX_RUN;
if (!count)
return count;
if (count > xsize) {
if (x + count > xsize) {
return -1;
}
x += count;
if (pixel & RLE_COPY_FLAG) {
while(count--) {
memcpy(dest, src, 2);
Expand Down