[NetBSD] cmdline() can raise MemoryError #1526
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Do not overallocate the buffer prompting for KERN_ARGMAX. It also fixes the code as KERN_ARGMAX was received into a size_t type, while kernel returned int. It caused argmax to contain garbage and allocation was randomly crashing with new jemalloc in the basesystem. New code prompts for exact buffer size before allocation and stores argv[] inside it. Bug investigated by Leonardo Taccari.
This header was removed from the OS as it was empty.
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What was the problem with cmdline? It got truncated? |
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malloc(3) returned NULL for buffer of size with garbage |
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Hello giampaolo,
giampaolo writes:
What was the problem with cmdline? It got truncated?
At least calling psutil.Process(pid).as_dict() lead to MemoryError,
e.g.:
```
| % python3.7
| Python 3.7.3 (default, May 3 2019, 17:54:14)
| [GCC 7.4.0] on netbsd8
| Type "help", "copyright", "credits" or "license" for more information.
| >>> import psutil
| >>> psutil.Process(1).as_dict()
| Traceback (most recent call last):
| File "<stdin>", line 1, in <module>
| File "/usr/pkg/lib/python3.7/site-packages/psutil/__init__.py", line 638, in as_dict
| ret = meth()
| File "/usr/pkg/lib/python3.7/site-packages/psutil/__init__.py", line 790, in cmdline
| return self._proc.cmdline()
| File "/usr/pkg/lib/python3.7/site-packages/psutil/_psbsd.py", line 562, in wrapper
| return fun(self, *args, **kwargs)
| File "/usr/pkg/lib/python3.7/site-packages/psutil/_psbsd.py", line 666, in cmdline
| return cext.proc_cmdline(self.pid)
| MemoryError
```
That was because in psutil_get_cmd_args() the kern.argmax sysctl(3)
```
char *
psutil_get_cmd_args(pid_t pid, size_t *argsize) {
int mib[4];
ssize_t st;
size_t argmax;
size_t size;
char *procargs = NULL;
mib[0] = CTL_KERN;
mib[1] = KERN_ARGMAX;
size = sizeof(argmax);
st = sysctl(mib, 2, &argmax, &size, NULL, 0);
if (st == -1) {
PyErr_SetFromErrno(PyExc_OSError);
return NULL;
procargs = (char *)malloc(argmax);
if (procargs == NULL) {
PyErr_NoMemory();
return NULL;
[...]
```
Before calling sysctl() `size' was 8, after calling it `size' was 4.
However, later when calling `malloc(argmax)' `argmax' contained
uninitialized data and thus failing.
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I plan to submit implementation of missing features for NetBSD, but I will do it with 1 PR after another. |
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Thanks, merged.
Sounds sweet. I am looking forward to that. |
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sys/user.hfor NetBSDpsutil_get_cmd_args