Bug 611672 – x11-libs/gdk-pixbuf: (CVE-2017-6312) Possible out-of-bounds read or undefined behavior in io-ico.c

• Status: RESOLVED DUPLICATE of bug 611390
• Product: Gentoo Security

[Description Ian Zimmerman 2017-03-04 01:40:57 UTC]

According to the upstream tracker (see ${URL}):

Before the patch to bug 313818 (https://bugzilla.gnome.org/show_bug.cgi?id=313818) it was clear it was possible to overflow State->HeaderSize in io-ico.c. See line 334:

State->HeaderSize = entry->DIBoffset + INFOHEADER_SIZE;

So a check of (State->HeaderSize < 0) was added after this operation. However, I noticed that with optimization compilation flags, this check never took place. Specifically when the project was compiled with gcc with the flags "-O1 -fstrict-overflow -ftree-vrp" (or anything including these, such as -O2 or -O3). You can read about these flags to understand why this happens.

This is a problem because I know that many distributions do default to allowing optimizations when building packages and I believe the default of JHBuild is to compile with -O2.

This leads to a possible out-of-bounds read of BIH later in line 362
From line 359:
BIH = Data+entry->DIBoffset;


Reproducible: Always

[Comment 1 Agostino Sarubbo 2017-03-04 10:59:36 UTC]

*** This bug has been marked as a duplicate of bug 611390 ***