* possible regression of ptrace on 2.6.26-rc1
[not found] ` <20080506080159.0638E26FA20@magilla.localdomain>
@ 2008-05-07 9:20 ` wenji huang
2008-05-08 20:11 ` Roland McGrath
0 siblings, 1 reply; 2+ messages in thread
From: wenji huang @ 2008-05-07 9:20 UTC (permalink / raw)
To: linux-kernel
[-- Attachment #1: Type: text/plain, Size: 625 bytes --]
Hi,
When I tried the test case (ptrace-syscall-ret) on 2.6.26-rc1 kernel,
found it always fails, but could pass on previous ones.
Here is the result (both in x86 and x86_64 box):
[wjhuang@10-182-121-27 single-test]$ ./ptrace-syscall-ret
./ptrace-syscall-ret: PTRACE_CONT, pid 17315, retvalue -1: No such process
In the case, a child is created and kept in syscall loop. The parent
will trace the syscall and kill the child at last. It seems the child
is early exited, but should stay in infinite loop. Is this my
misunderstanding or actual regression of kernel?
The test case is attached to the mail.
Thanks,
Wenji
[-- Attachment #2: ptrace-syscall-ret.c --]
[-- Type: text/x-csrc, Size: 2014 bytes --]
#include <signal.h>
#include <sys/wait.h>
#include <sys/ptrace.h>
#include <sys/user.h>
#include <unistd.h>
#include <sched.h>
#include <assert.h>
#include <asm/unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <error.h>
#include <errno.h>
#if defined __x86_64__ || defined __i386__
#define LOOP 10
static pid_t child;
static void
cleanup (void)
{
if (child != 0)
kill (child, SIGKILL);
}
static void
handler_fail (int signo)
{
cleanup ();
signal (SIGABRT, SIG_DFL);
assert (0);
}
int main(int argc, char **argv) {
int status, j;
long l;
pid_t pid;
setbuf (stdout, NULL);
atexit (cleanup);
signal (SIGABRT, handler_fail);
child = fork();
switch (child)
{
case -1:
assert(0);
case 0:
{ l = ptrace(PTRACE_TRACEME, 0, 0, 0);
assert(l==0);
raise(SIGSTOP);
while (1) {
l = access(".",R_OK);
assert(l==0);
}
assert(0); //not reached
} //end child
default:
break;
}
pid = waitpid(child, &status, 0);
assert(pid==child);
assert(WIFSTOPPED(status));
assert(WSTOPSIG(status) == SIGSTOP);
l = ptrace(PTRACE_SYSCALL,child, 0, 0);
assert(l==0);
j = 0;
while (j < LOOP){
pid = waitpid(child, &status, 0);
assert(child==pid);
assert(WIFSTOPPED(status));
assert(WSTOPSIG(status) == SIGTRAP);
l = ptrace(PTRACE_SYSCALL, child, 0, 0);
assert(l==0);
j++;
} //end loop
l = ptrace(PTRACE_CONT, child, 0, SIGKILL);
//if the following statement, always successful
//l = ptrace(PTRACE_KILL, child, 0,0);
if (l < 0) {
error (0, errno,"PTRACE_CONT, pid %ld, retvalue %ld",(long)child,l);
return 1;
}
else
assert(l==0);
pid = waitpid(child, &status, 0);
assert(child==pid);
if (WIFEXITED(status) && WTERMSIG(status)!=SIGKILL)
return 1;
return 0;
} //end main
#else
int main(int argc, char **argv) {
return 77;
}
#endif
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