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Added checks in PNG_pvt::write_info (fix SEGFAULT after "PCS illuminant is not D50" libpng error) #3535

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merged 1 commit into from
Aug 30, 2022
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Added checks in PNG_pvt::write_info (fix SEGFAULT after "PCS illuminant is not D50" libpng error) #3535

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19 changes: 18 additions & 1 deletion src/png.imageio/png_pvt.h
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Original file line number Diff line number Diff line change
Expand Up @@ -558,8 +558,9 @@ put_parameter(png_structp& sp, png_infop& ip, const std::string& _name,


/// Writes PNG header according to the ImageSpec.
/// \return empty string on success, error message on failure.
///
inline void
inline const std::string
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Mostly for my own curiosity: what purpose does the const serve here?

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This const is in every other functions returning an error std::string, so I kept it to keep a consistent code-style.

write_info(png_structp& sp, png_infop& ip, int& color_type, ImageSpec& spec,
std::vector<png_text>& text, bool& convert_alpha, float& gamma)
{
Expand All @@ -569,10 +570,14 @@ write_info(png_structp& sp, png_infop& ip, int& color_type, ImageSpec& spec,
else
spec.set_format(TypeDesc::UINT16); // best precision available

if (setjmp(png_jmpbuf(sp))) // NOLINT(cert-err52-cpp)
return "Could not set PNG IHDR chunk";
png_set_IHDR(sp, ip, spec.width, spec.height, spec.format.size() * 8,
color_type, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
PNG_FILTER_TYPE_DEFAULT);

if (setjmp(png_jmpbuf(sp))) // NOLINT(cert-err52-cpp)
return "Could not set PNG oFFs chunk";
png_set_oFFs(sp, ip, spec.x, spec.y, PNG_OFFSET_PIXEL);

// PNG specifically dictates unassociated (un-"premultiplied") alpha
Expand All @@ -583,14 +588,20 @@ write_info(png_structp& sp, png_infop& ip, int& color_type, ImageSpec& spec,

string_view colorspace = spec.get_string_attribute("oiio:ColorSpace");
if (Strutil::iequals(colorspace, "Linear")) {
if (setjmp(png_jmpbuf(sp))) // NOLINT(cert-err52-cpp)
return "Could not set PNG gAMA chunk";
png_set_gAMA(sp, ip, 1.0);
} else if (Strutil::istarts_with(colorspace, "Gamma")) {
Strutil::parse_word(colorspace);
float g = Strutil::from_string<float>(colorspace);
if (g >= 0.01f && g <= 10.0f /* sanity check */)
gamma = g;
if (setjmp(png_jmpbuf(sp))) // NOLINT(cert-err52-cpp)
return "Could not set PNG gAMA chunk";
png_set_gAMA(sp, ip, 1.0f / gamma);
} else if (Strutil::iequals(colorspace, "sRGB")) {
if (setjmp(png_jmpbuf(sp))) // NOLINT(cert-err52-cpp)
return "Could not set PNG gAMA and cHRM chunk";
png_set_sRGB_gAMA_and_cHRM(sp, ip, PNG_sRGB_INTENT_ABSOLUTE);
}

Expand All @@ -599,6 +610,8 @@ write_info(png_structp& sp, png_infop& ip, int& color_type, ImageSpec& spec,
ICC_PROFILE_ATTR);
if (icc_profile_parameter != NULL) {
unsigned int length = icc_profile_parameter->type().size();
if (setjmp(png_jmpbuf(sp))) // NOLINT(cert-err52-cpp)
return "Could not set PNG iCCP chunk";
#if OIIO_LIBPNG_VERSION > 10500 /* PNG function signatures changed */
unsigned char* icc_profile
= (unsigned char*)icc_profile_parameter->data();
Expand Down Expand Up @@ -658,6 +671,8 @@ write_info(png_structp& sp, png_infop& ip, int& color_type, ImageSpec& spec,
} else if (yres == 0.0f) {
yres = xres * (paspect ? paspect : 1.0f);
}
if (setjmp(png_jmpbuf(sp))) // NOLINT(cert-err52-cpp)
return "Could not set PNG pHYs chunk";
png_set_pHYs(sp, ip, (png_uint_32)(xres * scale),
(png_uint_32)(yres * scale), unittype);
}
Expand All @@ -673,6 +688,8 @@ write_info(png_structp& sp, png_infop& ip, int& color_type, ImageSpec& spec,

png_write_info(sp, ip);
png_set_packing(sp); // Pack 1, 2, 4 bit into bytes

return "";
}


Expand Down
10 changes: 8 additions & 2 deletions src/png.imageio/pngoutput.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -197,8 +197,14 @@ PNGOutput::open(const std::string& name, const ImageSpec& userspec,
png_set_option(m_png, PNG_SKIP_sRGB_CHECK_PROFILE, PNG_OPTION_ON);
#endif

PNG_pvt::write_info(m_png, m_info, m_color_type, m_spec, m_pngtext,
m_convert_alpha, m_gamma);
s = PNG_pvt::write_info(m_png, m_info, m_color_type, m_spec, m_pngtext,
m_convert_alpha, m_gamma);

if (s.length()) {
close();
errorfmt("{}", s);
return false;
}

m_dither = (m_spec.format == TypeDesc::UINT8)
? m_spec.get_int_attribute("oiio:dither", 0)
Expand Down