554142 - cairo-xlib-surface.c calls a macro with a side-effect in its argument

Status: RESOLVED DUPLICATE of bug 562746

(Core :: Graphics, defect)

Description

[Blake Kaplan (:mrbkap) (inactive)]

Attachment: Fix?

The code in question is:

do {
    *n++ = bswap_32 (*d++);
} while (--c);

bswap_32 is conditionally defined to use byteswap.h based on HAVE_BYTESWAP_H. If that macro is defined, then it appears that the macros defined in byetswap.h are side-effect safe (that is, they sample the parameter once and operate on the sample). If !HAVE_BYTESWAP_H, however, the macro evaluates its parameter multiple times, leading to mangled data and potential crashes.

I'll attach a patch, though I'm not sure what the procedure is for fixing cairo bugs, so I might not be the best person to drive this.

Comment 1

[Joe Drew (not getting mail)]

Comment on attachment 434019 [details] [diff] [review]
Fix?

We should just fix the version of bswap_32 in cairo_wideint_type_private.h.

Comment 2

[JP Rosevear [:jpr]]

This was fixed upstream and imported in bug 562746

commit ce3ad6f41edf86ed6914f4d7f364111eba42ca65
Author: Chris Wilson <[e-mail]>
Date:   Wed Mar 31 08:21:17 2010 +0100

    xlib: Avoid multiple evaluations inside bswap_*() macro.
    
    Fixes:
      Fonts are not readable if remote display to a machine with different
      endian.
      https://bugzilla.mozilla.org/show_bug.cgi?id=526977
    
    Reported-and-tested-by: Ginn Chen <[e-mail]>