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top on Fedora error #1567

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iapaddler opened this issue Jun 28, 2023 · 1 comment · Fixed by #1572
Closed

top on Fedora error #1567

iapaddler opened this issue Jun 28, 2023 · 1 comment · Fixed by #1572
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bug Something isn't working libscope

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@iapaddler
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On Fedora desktop
LD_PRELOAD=/usr/lib/appscope/libscope.so top
results in:
unknown terminal type
top does not start
@iapaddler iapaddler added bug Something isn't working libscope labels Jun 28, 2023
michalbiesek added a commit to michalbiesek/appscope that referenced this issue Jul 3, 2023
@michalbiesek
Modify __sprintf_chk call
1e833a5 
Here is the implementation called on Fedora:

23│ int
24│ ___sprintf_chk (char *s, int flag, size_t slen, const char *format, ...)
25│ {
26│   /* For flag > 0 (i.e. __USE_FORTIFY_LEVEL > 1) request that %n
27│      can only come from read-only format strings.  */
28│   unsigned int mode = (flag > 0) ? PRINTF_FORTIFY : 0;
29│   va_list ap;
30│   int ret;
31│
32│   /* Regardless of the value of flag, let __vsprintf_internal know that
33│      this is a call from *printf_chk.  */
34│   mode |= PRINTF_CHK;
35│
36│   if (slen == 0)
37│     __chk_fail ();
38│
39|   va_start (ap, format);
40│├─>   ret = __vsprintf_internal (s, slen, format, ap, mode);
41│   va_end (ap);
42│
43│   return ret;
44│ }

Fixes criblio#1567
michalbiesek added a commit to michalbiesek/appscope that referenced this issue Jul 3, 2023
@michalbiesek
Add Fedora integration` test
094c29e 
- add minimial nsterm example which reflects the
  issue with `top`

Ref: criblio#1567
michalbiesek added a commit to michalbiesek/appscope that referenced this issue Jul 3, 2023
@michalbiesek
Modify __sprintf_chk call in wrap.c
da0f88e 
The problematic code resides in `_nc_read_entry2`.

```
char filename[PATH_MAX]
...

    _nc_SPRINTF(filename, _nc_SLIMIT(PATH_MAX)
		"%.*s", PATH_MAX - 1, name);
```

The variable `name` above is set to "xterm".

In the absence of libscope.so, the aforementioned function assigns
the value "xterm" to the filename variable. However, when libscope.so
is loaded, the function assigns "xter" to filename.

In the Fedora environment, the invocation of `__sprintf_chk`
leads to the execution of `__vsprintf_internal`:

```
   va_start (ap, format);
   ret = __vsprintf_internal(s, slen, format, ap, mode);
   va_end (ap);
```

On the other hand, AppScope utilizes the following call:

```
   va_start(ap, format);
   rc = vsnprintf(str, strlen, format, ap);
   va_end(ap);
```

It should be noted that the implementations of `vsnprintf` and
`__vsprintf_internal` differ in standard library. This commit replaces
the `vsnprintf` call with `vsprintf` to address the discrepancy.

Fixes criblio#1567
michalbiesek added a commit to michalbiesek/appscope that referenced this issue Jul 4, 2023
@michalbiesek
Add Fedora integration` test
850da8f 
- add minimial nsterm example which reflects the
  issue with `top`

Ref: criblio#1567
michalbiesek added a commit to michalbiesek/appscope that referenced this issue Jul 4, 2023
@michalbiesek
Modify __sprintf_chk call in wrap.c
e3e94ad 
The problematic code resides in `_nc_read_entry2`.

```
char filename[PATH_MAX]
...

    _nc_SPRINTF(filename, _nc_SLIMIT(PATH_MAX)
		"%.*s", PATH_MAX - 1, name);
```

The variable `name` above is set to "xterm".

In the absence of libscope.so, the aforementioned function assigns
the value "xterm" to the filename variable. However, when libscope.so
is loaded, the function assigns "xter" to filename.

In the Fedora environment, the invocation of `__sprintf_chk`
leads to the execution of `__vsprintf_internal`:

```
   va_start (ap, format);
   ret = __vsprintf_internal(s, slen, format, ap, mode);
   va_end (ap);
```

On the other hand, AppScope utilizes the following call:

```
   va_start(ap, format);
   rc = vsnprintf(str, strlen, format, ap);
   va_end(ap);
```

It should be noted that the implementations of `vsnprintf` and
`__vsprintf_internal` differ in standard library. This commit replaces
the `vsnprintf` call with `vsprintf` to address the discrepancy.

Fixes criblio#1567
@michalbiesek
Copy link
Contributor

The #1572 address the issue.

The root cause:

The problematic code resides in _nc_read_entry2 in curses library.

char filename[PATH_MAX]
...

    _nc_SPRINTF(filename, _nc_SLIMIT(PATH_MAX)
		"%.*s", PATH_MAX - 1, name);

The variable name above is set to "xterm".

In the absence of libscope.so, the aforementioned function assigns
the value "xterm" to the filename variable. However, when libscope.so
is loaded, the function assigns "xter" to filename.

In the Fedora environment, the invocation of __sprintf_chk
leads to the execution of __vsprintf_internal:

   va_start (ap, format);
   ret = __vsprintf_internal(s, slen, format, ap, mode);
   va_end (ap);

On the other hand, AppScope utilizes the following call:

   va_start(ap, format);
   rc = vsnprintf(str, strlen, format, ap);
   va_end(ap);

It should be noted that the implementations of vsnprintf and
__vsprintf_internal differ in standard library. This commit replaces
the vsnprintf call with vsprintf to address the discrepancy.

The easiest way to test it is to try to scope top on Fedora.
Integration test was added to cover the issue.

michalbiesek added a commit that referenced this issue Jul 5, 2023
@michalbiesek
Add Fedora integration` test
e34e51e 
- add minimial nsterm example which reflects the
  issue with `top`

Ref: #1567
michalbiesek added a commit that referenced this issue Jul 5, 2023
@michalbiesek
Modify __sprintf_chk call in wrap.c
52500f5 
The problematic code resides in `_nc_read_entry2`.

```
char filename[PATH_MAX]
...

    _nc_SPRINTF(filename, _nc_SLIMIT(PATH_MAX)
		"%.*s", PATH_MAX - 1, name);
```

The variable `name` above is set to "xterm".

In the absence of libscope.so, the aforementioned function assigns
the value "xterm" to the filename variable. However, when libscope.so
is loaded, the function assigns "xter" to filename.

In the Fedora environment, the invocation of `__sprintf_chk`
leads to the execution of `__vsprintf_internal`:

```
   va_start (ap, format);
   ret = __vsprintf_internal(s, slen, format, ap, mode);
   va_end (ap);
```

On the other hand, AppScope utilizes the following call:

```
   va_start(ap, format);
   rc = vsnprintf(str, strlen, format, ap);
   va_end(ap);
```

It should be noted that the implementations of `vsnprintf` and
`__vsprintf_internal` differ in standard library. This commit replaces
the `vsnprintf` call with `vsprintf` to address the discrepancy.

Fixes #1567
@michalbiesek michalbiesek linked a pull request Jul 5, 2023 that will close this issue
top on Fedora error 1567 #1572
Merged
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top on Fedora error 1567 criblio/appscope
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@iapaddler @michalbiesek