Re: -fstack-clash-protection triggers something in setfstab()

Am 2025-03-15 14:33, schrieb Kyle Evans:
> [+grembo@ for iocage]
> 
> On 3/15/25 06:26, Alexander Leidinger wrote:
>> Am 2025-02-26 16:20, schrieb Alexander Leidinger:
>>> Hi,
>>> 
>>> the working system is from 2025-01-25-141603, the non working system 
>>> is from 2025-02-21-115311.
>>> 
>>> I'm not sure what the issue is exactly. I have traced down the change 
>>> of behavior to
>>> ---snip---
>>> if not LIBC.setfstab(fstab_file_path.encode()):
>>> ---snip---
>>> 
>>> In the working case LIBC.setfstab returns true (so with the not it 
>>> doesn't take this branch), and in the non-working case it returns 
>>> false (so with the not it takes this branch).
>>> 
>>> Is someone aware of a change in this area? Searching for it (https:// 
>>> cgit.freebsd.org/src/log/?qt=grep&q=setfstab) only brings the initial 
>>> commit.
>> 
>> Interestingly my own commit triggers this issue.
>> 
>> I bisected and commit 1c2ae9233b0ed4f6b92c59c0e4026f6ddc073e4a is 
>> causing this. This is the first ref which triggers the issue that 
>> iocage can not mount filesystems anymore. And the failing call in 
>> iocage seems to be the python LIBC.setfstab() call. And this only 
>> triggers, when the basesystem is compiled with the stack clash 
>> protection. I do not see any obvious issue in our setfstab code. 
>> Anyone with an idea?
>> 
> setfstab() implementation seems more or less fine, but it's hard to 
> tell what's going on with iocage there.  setfstab(3) doesn't actually 
> have a return value in any version of FreeBSD, so I guess it's picking 
> up some sort of garbage as the return value.
> 
> Looking at the context, you can only tell if the open failed with the 
> subsequent getfsent()/setfsent(); that branch should probably just be 
> removed entirely, and the initial getfsent() might be worth 
> error-checking for potential error or premature EOF.

I tried this, and it works:
---snip---
# diff -u 
/usr/local/lib/python3.11/site-packages/iocage_lib/ioc_fstab_ok.py 
/usr/local/lib/python3.11/site-packages/io
cage_lib/ioc_fstab.py
--- /usr/local/lib/python3.11/site-packages/iocage_lib/ioc_fstab_ok.py  
2025-02-26 14:54:37.381812000 +0100
+++ /usr/local/lib/python3.11/site-packages/iocage_lib/ioc_fstab.py     
2025-03-16 12:55:30.496569000 +0100
@@ -159,15 +159,16 @@
          )
          fstab_list = []
          with FSTAB_LOCK:
-            if not LIBC.setfstab(fstab_file_path.encode()):
-                iocage_lib.ioc_common.logit(
-                    {
-                        'level': 'EXCEPTION',
-                        'message': f'Unable to open {fstab_file_path}'
-                    },
-                    _callback=self.callback,
-                    silent=self.silent
-                )
+            LIBC.setfstab(fstab_file_path.encode())
+            #if not LIBC.setfstab(fstab_file_path.encode()):
+            #    iocage_lib.ioc_common.logit(
+            #        {
+            #            'level': 'EXCEPTION',
+            #            'message': f'Unable to open {fstab_file_path}'
+            #        },
+            #        _callback=self.callback,
+            #        silent=self.silent
+            #    )
              try:
                  set_fstab_path = ensure_unicode_str(LIBC.getfstab())
                  if set_fstab_path != fstab_file_path:
---snip---

Bye,
Alexander.

-- 
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