Bugs with qualify in strace 4.5.15

[Xiaoning Ding]

Hi, all

I think these two parts of code in strace version 4.5.15 may be bugs.

1. function qualify() in syscall.c.

The sizes of sysent0, sysent1, and systen2 are usually smaller than
MAX_QUALS, which is defined as 5000 for MIPS+LINUX and 2048 for
others.  The inner loop accessing syscall entries beyond the defined
scope.

The related source code is quoted below.
       for (p = strtok(s, ","); p; p = strtok(NULL, ",")) {
                if (opt->bitflag == QUAL_TRACE && (n = lookup_class(p)) > 0) {
                        for (i = 0; i < MAX_QUALS; i++) {
                                if (sysent0[i].sys_flags & n)
                                        qualify_one(i, opt, not, 0);
#if SUPPORTED_PERSONALITIES >= 2
                                if (sysent1[i].sys_flags & n)
                                        qualify_one(i, opt, not, 1);
#endif /* SUPPORTED_PERSONALITIES >= 2 */

#if SUPPORTED_PERSONALITIES >= 3
                                if (sysent2[i].sys_flags & n)
                                        qualify_one(i, opt, not, 2);
#endif /* SUPPORTED_PERSONALITIES >= 3 */
                        }
                        continue;
   }


2.  function dumpio() in syscall.c.

Before dumpstr() or dumpiov() is called,  qual_flags[tcp->u_arg[0]] is
examined against the corresponding qualifier flag. eg.
 if (qual_flags[tcp->u_arg[0]] & QUAL_WRITE)
       dumpstr(...)..

However, tcp->u_arg[0] does not contain any syscall number. Should it
be replaced with tcp->scno?


Xiaoning