[File] [PATCH] Issue with libmagic and floating point exceptions

[Christos Zoulas]

On 2022-12-14 8:15 am, Vincent Mihalkovic wrote:
> Hi,
> 
> The "Floating point exception (core dumped)" occurred when using
> libmagic internals
> 
> on software with floating point exceptions enabled (FE_INVALID).
> 
> Sample of what happens:
> """
> #include <stdio.h>
> #include <math.h>
> #include <fenv.h>
> 
> int feenableexcept(int);
> int fedisableexcept(int);
> 
> """
> int
> main(int argc, char *argv[])
> {
>   union {
>     int   i;
>     float f;
>   } u[2];
>   fedisableexcept(FE_ALL_EXCEPT);
>   feenableexcept(FE_INVALID);
>   u[0].i = -1;  // NaN
>   u[1].f = 1;
>   printf("%d\n", u[0].f < u[1].f);
>   //printf("%d\n", isless(u[0].f, u[1].f));
>   return 0;
> }
> """
> 
> $ gcc test.c -lm
> $ ./a.out
> Floating point exception (core dumped)
> 
> The proposed fix (by Paolo Andrade) added a simple check using macros
> (__builtin_is{less,greater,unordered}) from math.h.
> 
> More detailed description in:
> https://bugzilla.redhat.com/show_bug.cgi?id=2061557.
> 
> Vincent Mihalkovic

Committed, thanks!

christos