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From: John Levon <levon@movementarian.org>
To: smatch@vger.kernel.org, linux-sparse@vger.kernel.org
Cc: yuri.pankov@nexenta.com
Subject: noreturn attribute doesn't work in smatch
Date: Thu, 15 Aug 2019 01:53:28 +0100	[thread overview]
Message-ID: <20190815005328.GA8004@movementarian.org> (raw)


./smatch: a.c:20 main() error: double free of 'str'

given:

```
#include <stdlib.h>
#include <string.h>

__attribute__((__noreturn__)) void
die(void)
{
        exit(1);
}

int
main(void)
{
        char *str = strdup("test");

        if (str != NULL) {
                free(str);
                die();
        }

        free(str);

        return (0);
}
```

As far as I can figure out, this looks like a sparse problem: an
'inline' or 'extern' specifier in this position gets marked as the
relevant MOD_* flag for the function, but the noreturn doesn't bubble
up in the same way. Some quick lame attempts to add ctx->is_noreturn did
not go well.

I think this might be the underlying issue behind sparse's failing test
validation/function-redecl2.c but I'm not positive.

We can do:

```
#ifdef __CHECKER__
#define SMATCH_NORETURN __attribute__((__noreturn__))
#else
#define SMATCH_NORETURN /* would break gcc otherwise */
#endif

__attribute__((__noreturn__)) void
die(void) SMATCH_NORETURN
{
```

but it's ... unlovely.

Any thoughts?

thanks
john

next             reply	other threads:[~2019-08-15  0:53 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-15  0:53 John Levon [this message]
2019-08-15 11:12 ` noreturn attribute doesn't work in smatch John Levon
2019-08-22 13:30   ` Dan Carpenter
2019-08-22 13:46     ` John Levon
2019-08-22 15:05       ` Dan Carpenter
2019-08-22 15:29         ` John Levon

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