Can't compile "iwlwifi" module in Linux

Submitted ⁨⁨8⁩ ⁨months⁩ ago⁩ by ⁨nothingness@lemmy.world⁩ to ⁨programming@programming.dev⁩

I’m trying to build iwlwifi module manually and for my needs.

git.kernel.org/pub/scm/linux/kernel/…/wireless/

When I run Makefile as make, I get:

subcmd-util.h: In function ‘xrealloc’:
subcmd-util.h:58:31: error: pointer ‘ptr’ may be used after ‘realloc’ [-Werror=use-after-free]
   58 |                         ret = realloc(ptr, 1);
      |                               ^~~~~~~~~~~~~~~
subcmd-util.h:52:21: note: call to ‘realloc’ here
   52 |         void *ret = realloc(ptr, size);
      |                     ^~~~~~~~~~~~~~~~~~
subcmd-util.h:56:23: error: pointer ‘ptr’ may be used after ‘realloc’ [-Werror=use-after-free]
   56 |                 ret = realloc(ptr, size);
      |                       ^~~~~~~~~~~~~~~~~~
subcmd-util.h:52:21: note: call to ‘realloc’ here
   52 |         void *ret = realloc(ptr, size);
      |                     ^~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[4]: *** [/data/iwlwifi-fixes/tools/build/Makefile.build:97: /data/iwlwifi-fixes/tools/objtool/help.o] Error 1
make[3]: *** [Makefile:59: /data/iwlwifi-fixes/tools/objtool/libsubcmd-in.o] Error 2
make[2]: *** [Makefile:63: /data/iwlwifi-fixes/tools/objtool/libsubcmd.a] Error 2
make[1]: *** [Makefile:69: objtool] Error 2
make: *** [Makefile:1349: tools/objtool] Error 2

Why is it? How to fix it?

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Comments

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yardy_sardley@lemmy.ca ⁨8⁩ ⁨months⁩ ago
This would normally be a compiler warning, but someone has enabled the -Werror compiler option (probably in the makefile) which causes the compiler to treat all warnings as errors. You can just remove any -Werror flags from the makefile and it should compile properly.

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- nothingness@lemmy.world ⁨8⁩ ⁨months⁩ ago
  will try
  
  source
cbarrick@lemmy.world ⁨8⁩ ⁨months⁩ ago
Why is it?

The code hitting that error is here:

git.kernel.org/pub/scm/linux/…/subcmd-util.h

It looks fine to me.

What you are seeing is a warning that your compuler may have found a use-after-free bug, but I think this is a false positive. Your build is configured to turn this warning into a hard error.

How to fix it?

I think it will be difficult to know how to fix this without knowing more about your build setup. Are you passing any custom CFLAGS? What compiler and version are you using?

Also, here is someone asking about the same issue (in the same code) on Stack Exchange using GGC 12.1:

unix.stackexchange.com/…/linux-kernel-5-15-54-com…

This was the top result when Googling linux “-Werror=use-after-free”.

I believe you can disable this warning in this file by adding a pragma after the includes (line 8):

#pragma GCC diagnostic ignored "-Wuse-after-free"

See stackoverflow.com/…/selectively-remove-a-warning-…
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- litchralee@sh.itjust.works ⁨8⁩ ⁨months⁩ ago
  No objections to your answer to the OP’s question, but as a curiosity, I’m trying to figure out what the original xrealloc() function is trying to do.
  
  So far as I can tell, it tries a normal realloc() with the requested size, but if that fails, trys again with size=1. But strangely, it that fails, trys using the requested size a second time. And if that still fails, tries once more with size=1.
  
  source
- nothingness@lemmy.world ⁨8⁩ ⁨months⁩ ago
  I think it will be difficult to know how to fix this without knowing more about your build setup. Are you passing any custom CFLAGS? What compiler and version are you using?
  
  No.
  
  gcc --version gcc (GCC) 13.2.1 20230801
  
  The goal - simply compile it for now.
  
  source
  - cbarrick@lemmy.world ⁨8⁩ ⁨months⁩ ago
    If you don’t want to change the code, try disabling the use-after-free warning from the make call:
    
    make CFLAGS="-Wno-use-after-free"
    
    source
AlmightySnoo@lemmy.world ⁨8⁩ ⁨months⁩ ago
What revision are you using? Because I don’t see the ret = realloc(ptr, 1); line in github.com/torvalds/linux/blob/…/subcmd-util.h

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