Bug#731435: warning: iteration 55823u invokes undefined behavior [-Waggressive-loop-optimizations]

[Alberto Garcia]

On Mon, Apr 06, 2020 at 10:29:35AM +0200, Mathieu Malaterre wrote:

> http://git.dcmtk.org/?p=dcmtk.git;a=commit;h=180d9b9

I have to say that I don't see how the changes to jccolor.c solve the
problem ... the warning that we have is about this line:

 rgb_ycc_tab[i+G_Y_OFF] = FIX(0.58700) * i;

This is round(0.58700 * 65536) * 55823 = 2147510810, which exceeds
INT32_MAX and therefore cannot be stored in rgb_ycc_tab, no matter how
many casts you use.

Berto

Bug#731435: warning: iteration 55823u invokes undefined behavior [-Waggressive-loop-optimizations]

[Mathieu Malaterre]

Control: tags -1 patch

On Sun, Apr 5, 2020 at 8:27 PM Alberto Garcia  wrote:
>
> On Thu, Dec 05, 2013 at 02:00:59PM +0100, Mathieu Malaterre wrote:
> > /«PKGBUILDDIR»/Utilities/gdcmjpeg/jccolor.c: In function 'rgb_ycc_start':
> > /«PKGBUILDDIR»/Utilities/gdcmjpeg/jccolor.c:99:43: warning: iteration
> > 55823u invokes undefined behavior [-Waggressive-loop-optimizations]
> >  rgb_ycc_tab[i+G_Y_OFF] = FIX(0.58700) * i;
> >^
> > /«PKGBUILDDIR»/Utilities/gdcmjpeg/jccolor.c:97:3: note: containing loop
> >for (i = 0; i <= MAXJSAMPLE; i++) {
> >^
>
> This has already been reported upstream, and it seems exactly the same
> as #731433, which was fixed upstream in DCMTK:
>
>https://support.dcmtk.org/redmine/issues/759
>
> Berto
>

http://git.dcmtk.org/?p=dcmtk.git;a=commit;h=180d9b9

Bug#731435: warning: iteration 55823u invokes undefined behavior [-Waggressive-loop-optimizations]

[Alberto Garcia]

On Thu, Dec 05, 2013 at 02:00:59PM +0100, Mathieu Malaterre wrote:
> /«PKGBUILDDIR»/Utilities/gdcmjpeg/jccolor.c: In function 'rgb_ycc_start':
> /«PKGBUILDDIR»/Utilities/gdcmjpeg/jccolor.c:99:43: warning: iteration
> 55823u invokes undefined behavior [-Waggressive-loop-optimizations]
>  rgb_ycc_tab[i+G_Y_OFF] = FIX(0.58700) * i;
>^
> /«PKGBUILDDIR»/Utilities/gdcmjpeg/jccolor.c:97:3: note: containing loop
>for (i = 0; i <= MAXJSAMPLE; i++) {
>^

This has already been reported upstream, and it seems exactly the same
as #731433, which was fixed upstream in DCMTK:

   https://support.dcmtk.org/redmine/issues/759

Berto

Bug#731435: warning: iteration 55823u invokes undefined behavior [-Waggressive-loop-optimizations]

[Mathieu Malaterre]

Package: gdcm

gdcm currently compiles with:

cd /«PKGBUILDDIR»/obj-i486-linux-gnu/Utilities/gdcmjpeg/8 
/usr/bin/cc  -Dgdcmjpeg8_EXPORTS -g -O2 -fstack-protector
--param=ssp-buffer-size=4 -Wformat -Werror=format-security
-D_FORTIFY_SOURCE=2  -fPIC -I/«PKGBUILDDIR»/Utilities/gdcmjpeg/8
-I/«PKGBUILDDIR»/obj-i486-linux-gnu/Utilities/gdcmjpeg/8
-I/«PKGBUILDDIR»/obj-i486-linux-gnu/Utilities/gdcmjpeg-o
CMakeFiles/gdcmjpeg8.dir/__/jccolor.c.o   -c
/«PKGBUILDDIR»/Utilities/gdcmjpeg/jccolor.c
/«PKGBUILDDIR»/Utilities/gdcmjpeg/jccolor.c: In function 'rgb_ycc_start':
/«PKGBUILDDIR»/Utilities/gdcmjpeg/jccolor.c:99:43: warning: iteration
55823u invokes undefined behavior [-Waggressive-loop-optimizations]
 rgb_ycc_tab[i+G_Y_OFF] = FIX(0.58700) * i;
   ^
/«PKGBUILDDIR»/Utilities/gdcmjpeg/jccolor.c:97:3: note: containing loop
   for (i = 0; i = MAXJSAMPLE; i++) {
   ^
/usr/bin/cmake -E cmake_progress_report
/«PKGBUILDDIR»/obj-i486-linux-gnu/CMakeFiles


--
To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org
with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org