0-day: rebuild with new pdfium dll

[Antoine Martin]

Details here: ​New Chrome 0-day Bug Under Active Attacks – Update Your Browser Now!: the other resides in the PDFium (​CVE-2019-13721) library

[Antoine Martin]

  -> Cloning pdfium git repo...
Cloning into bare repository '/e/MINGW-packages/mingw-w64-pdfium-git/pdfium'...
      0 [main] git-remote-https 1233 child_info_fork::abort: \??\C:\msys32\usr\bin\msys-unistring-2.dll: Loaded to different address: parent(0x640000) != child(0x800000)
error: cannot fork() for fetch-pack: Resource temporarily unavailable
==> ERROR: Failure while downloading pdfium git repo
    Aborting...

[totaamwin32]

Modifying the PKGBUILD to try to build revision ​3976 and copying the patch file to the new name pdfium-3976.patch gives lots of rejects:

==> Starting prepare()...
can't find file to patch at input line 4
Perhaps you used the wrong -p or --strip option?
The text leading up to this was:
--------------------------
|diff -r -c pdfium.orig/build_gyp/gyp_pdfium pdfium/build_gyp/gyp_pdfium
|*** pdfium.orig/build_gyp/gyp_pdfium   2016-05-09 10:47:41.000000000 -0300
|--- pdfium/build_gyp/gyp_pdfium        2016-05-09 10:44:18.208997100 -0300
--------------------------
File to patch:
Skip this patch? [y]
Skipping patch.
2 out of 2 hunks ignored
can't find file to patch at input line 42
Perhaps you used the wrong -p or --strip option?
The text leading up to this was:
--------------------------
|diff -r -c pdfium.orig/core/fxcrt/fx_basic_util.cpp pdfium/core/fxcrt/fx_basic_util.cpp
|*** pdfium.orig/core/fxcrt/fx_basic_util.cpp   2016-05-09 10:47:41.000000000 -0300
|--- pdfium/core/fxcrt/fx_basic_util.cpp        2016-05-09 10:43:40.187642300 -0300
--------------------------
File to patch:
Skip this patch? [y]
Skipping patch.
2 out of 2 hunks ignored
can't find file to patch at input line 79
Perhaps you used the wrong -p or --strip option?
The text leading up to this was:
--------------------------
|diff -r -c pdfium.orig/core/fxcrt/include/fx_system.h pdfium/core/fxcrt/include/fx_system.h
|*** pdfium.orig/core/fxcrt/include/fx_system.h 2016-05-09 10:47:41.000000000 -0300
|--- pdfium/core/fxcrt/include/fx_system.h      2016-05-09 10:43:40.203267200 -0300
--------------------------
File to patch:
Skip this patch? [y]
Skipping patch.
1 out of 1 hunk ignored
can't find file to patch at input line 99
Perhaps you used the wrong -p or --strip option?
The text leading up to this was:
--------------------------
|diff -r -c pdfium.orig/core/fxge/win32/fx_win32_dwrite.cpp pdfium/core/fxge/win32/fx_win32_dwrite.cpp
|*** pdfium.orig/core/fxge/win32/fx_win32_dwrite.cpp    2016-05-09 10:47:42.000000000 -0300
|--- pdfium/core/fxge/win32/fx_win32_dwrite.cpp 2016-05-09 10:43:40.218892400 -0300
--------------------------
File to patch:
Skip this patch? [y]
Skipping patch.
1 out of 1 hunk ignored
patching file core/fxge/win32/fx_win32_gdipext.cpp
Hunk #1 FAILED at 691.
Hunk #2 FAILED at 706.
2 out of 2 hunks FAILED -- saving rejects to file core/fxge/win32/fx_win32_gdipext.cpp.rej
can't find file to patch at input line 158
Perhaps you used the wrong -p or --strip option?
The text leading up to this was:
--------------------------
|diff -r -c pdfium.orig/pdfium.gyp pdfium/pdfium.gyp
|*** pdfium.orig/pdfium.gyp     2016-05-09 10:47:42.000000000 -0300
|--- pdfium/pdfium.gyp  2016-05-09 10:43:40.218892400 -0300
--------------------------
File to patch:
Skip this patch? [y]
Skipping patch.
4 out of 4 hunks ignored
can't find file to patch at input line 323
Perhaps you used the wrong -p or --strip option?
The text leading up to this was:
--------------------------
|diff -r -c pdfium.orig/samples/samples.gyp pdfium/samples/samples.gyp
|*** pdfium.orig/samples/samples.gyp    2016-05-09 10:47:42.000000000 -0300
|--- pdfium/samples/samples.gyp 2016-05-09 10:43:40.218892400 -0300
--------------------------
File to patch:
Skip this patch? [y]
Skipping patch.
2 out of 2 hunks ignored
==> ERROR: A failure occurred in prepare().
    Aborting...

[totaamwin32]

Trying to build (with limited patching):

$ ninja
ninja: error: loading 'build.ninja': No such file or directory

Docs say we're supposed to use gn?

$ gn --help
gn.py: Could not find checkout in any parent of the current path.
This must be run inside a checkout.

What does this even mean?
I want to build your software, why is it so hard?
(makes autotools look easy!)

[Sergey]

pdfium is a Google project. Google (Chromium team) uses Ninja build system.
Try to run ninja with proper parameters:
ninja -C <directory> pdfium_all

For more details see ​https://pdfium.googlesource.com/pdfium/

[Antoine Martin]

@sergey: there are no build.ninja files anywhere, I believe that's where gn comes in.

[Sergey]

Replying to Antoine Martin:

@sergey: there are no build.ninja files anywhere, I believe that's where gn comes in.

Sure. 1st of all it's necessary to generate build configs:

gn gen <directory>

For example:

gn gen out/Default

And then

ninja -C out/Default pdfium_all

If you see error

gn.py: Could not find checkout in any parent of the current path.
This must be run inside a checkout.

your checkout is not full. I do not think it's possible to build pdfium with just clone the repository. It's necessary to checkout all dependencies. I've try official way and it did work on my Fedora:

mkdir repo
cd repo
gclient config --unmanaged https://pdfium.googlesource.com/pdfium.git
gclient sync
cd pdfium

[Antoine Martin]

​Security Risks of PDFium-based Apps and SDKs: The high number of reported PDFium vulnerabilities compared to some PDF libraries doesn’t necessarily imply an unusual degree of insecurity for open source; but it creates challenges for developers, DevSecOps?, and security teams.

[Antoine Martin]

Another option would be to cherry pick some of the fixes and apply them to the version in mingw.
Some of the fixes may not be needed.

ie:

• ​https://nvd.nist.gov/vuln/detail/CVE-2019-5868 Use after free in PDFium in Google Chrome prior to 76.0.3809.100 allowed a remote attacker to potentially exploit heap corruption via a crafted PDF file. ​Issue 983867: Security: Use-after-free in CPDFSDK_ActionHandler::ExecuteFieldAction
• ​https://nvd.nist.gov/vuln/detail/CVE-2019-13721 Use after free in PDFium in Google Chrome prior to 78.0.3904.87 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page. ​https://bugs.chromium.org/p/chromium/issues/detail?id=1013868 (no details yet)

Commits:

• ​Replace UnownedPtr with RetainPtr to parser objects in fpdfdoc
• ​Remove const from public fpdfview types

The last change in mingw: ​update to latest branch (2729) : Diego Sogari committed on May 9, 2016..

[Antoine Martin]

Replying to Sergey:

Sure. 1st of all it's necessary to generate build configs:
..
I do not think it's possible to build pdfium with just clone the repository.

Looks like they managed to do it in MSYS2.
Things have changed since the build file was made and adapting it to the new code is hard, so now I am leaning towards applying the fixes to that branch instead.
Here's the build file: ​https://github.com/msys2/MINGW-packages/blob/master/mingw-w64-pdfium-git/PKGBUILD.

And here is the patch I am most interested in applying: ​https://pdfium-review.googlesource.com/changes/pdfium~57854/revisions/8/patch?zip

If you want to try it, it should be trivial using an mswindows box:

• install ​MSYS2
• clone ​https://github.com/msys2/MINGW-packages
• go to MINGW-packages/mingw-w64-pdfium-git
• run makepkg -sCLf

[Antoine Martin]

Upstream ticket: ​update pdfium-git / git fetch fails.