[Bug analyzer/106283] RFE: analyzer handling of close_range and closefrom

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106283

David Malcolm <dmalcolm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
         Depends on|                            |126830
   Last reconfirmed|                            |2026-08-13
     Ever confirmed|0                           |1

--- Comment #1 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
$ cat t.c
#include <unistd.h>
#include <fcntl.h>

extern void closefrom(int lowfd);

void daemonize(void)
{
  int fd = open("/dev/null", O_RDWR);
  if (fd < 0)
    return;

  dup2(fd, 0);
  dup2(fd, 1);
  dup2(fd, 2);

  if (fd > 2)
    closefrom(3);  /* closes fd, but analyzer doesn't know */
}

$ gcc -fanalyzer -c t.c
t.c: In function 'daemonize':
t.c:18:1: warning: leak of file descriptor 'fd' [-Wanalyzer-fd-leak]

Trunk: https://godbolt.org/z/bGfn5n9Tz

Seen in the August 2026 OpenScanHub mass scan of Fedora 45 (PR 126830)
affecting audit, bash, and others (est. ~50-60 FPs).


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126830
[Bug 126830] Tracker bug for -fanalyzer false positives seen in August 2026
OpenScanHub mass scan