buffer overflow check bug

DISCUSSION Dan Carpenter 3 participants 5 messages Jun 18, 2012 – Jun 22, 2012 10 messages not in the archive Sparse checker

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Dan Carpenter

author

2012-06-18 19:53 UTC #10 lore raw

Gar... I have no idea. That seems like an issue in sparse.

Does anyone know why MOD_NORETURN gets set for:
extern void my_exit(const char*, ...) __attribute__ ((__noreturn__));

but not for:
extern __attribute__ ((__noreturn__)) void my_exit(const char*, ...);

GCC seems to accept both formats.

regards,
dan carpenter

Josh Triplett

2012-06-18 20:04 UTC #11 lore raw

Quoted 9 lines · Dan Carpenter

Gar... I have no idea. That seems like an issue in sparse.
Does anyone know why MOD_NORETURN gets set for:
extern void my_exit(const char*, ...) __attribute__ ((__noreturn__));
but not for:
extern __attribute__ ((__noreturn__)) void my_exit(const char*, ...);
GCC seems to accept both formats.

I wonder if the latter gets incorrectly parsed as though the attribute attached to "void" rather than "my_exit"?

- Josh Triplett

Dan Carpenter

author

2012-06-18 20:25 UTC #12 lore raw

Quoted 6 lines · Josh Triplett

Quoted 5 lines · Dan Carpenter
Gar... I have no idea. That seems like an issue in sparse.
Does anyone know why MOD_NORETURN gets set for:
extern void my_exit(const char*, ...) __attribute__ ((__noreturn__));

Quoted 8 lines

Quoted 4 lines
but not for:
extern __attribute__ ((__noreturn__)) void my_exit(const char*, ...);
GCC seems to accept both formats.
I wonder if the latter gets incorrectly parsed as though the attribute attached to "void" rather than "my_exit"?

I put a:

	printf("%d %d token = %s\n", token->pos.line, token->pos.pos, token->ident->name);

in handle_attributes() and it only prints when the attribute is at the end.

regards,
dan carpenter

Xi Wang

2012-06-19 20:37 UTC #13 lore raw

In reply to Dan Carpenter

Quoted 9 lines · Dan Carpenter

Gar... I have no idea. That seems like an issue in sparse.
Does anyone know why MOD_NORETURN gets set for:
extern void my_exit(const char*, ...) __attribute__ ((__noreturn__));
but not for:
extern __attribute__ ((__noreturn__)) void my_exit(const char*, ...);
GCC seems to accept both formats.

Which version of sparse are you using? Everything looks good to me here.

  extern void my_exit(const char*, ...) __attribute__ ((__noreturn__));
  extern __attribute__ ((__noreturn__)) void another_exit(const char*, ...);
  void foo(void) { my_exit(""); }
  void bar(void) { another_exit(""); }

My backend "splay" emits:

declare void @my_exit(i8*, ...) noreturn
declare void @another_exit(i8*, ...) noreturn
...

The noreturn attribute is set simply by:

  if (sym->ctype.modifiers & MOD_NORETURN)
      LLVMAddFunctionAttr(func, LLVMNoReturnAttribute);

- xi

Dan Carpenter

author

2012-06-22 12:32 UTC #14 lore raw

Quoted 7 lines · Xi Wang

Quoted 5 lines · Dan Carpenter
Gar... I have no idea. That seems like an issue in sparse.
Does anyone know why MOD_NORETURN gets set for:
extern void my_exit(const char*, ...) __attribute__ ((__noreturn__));

Quoted 6 lines

Quoted 4 lines
but not for:
extern __attribute__ ((__noreturn__)) void my_exit(const char*, ...);
GCC seems to accept both formats.
Which version of sparse are you using? Everything looks good to me here.

I'm on sparse 0.4.4. Which version are you on?

Quoted 8 lines

  extern void my_exit(const char*, ...) __attribute__ ((__noreturn__));
  extern __attribute__ ((__noreturn__)) void another_exit(const char*, ...);
  void foo(void) { my_exit(""); }
  void bar(void) { another_exit(""); }

My backend "splay" emits:

Quoted 8 lines

declare void @my_exit(i8*, ...) noreturn
declare void @another_exit(i8*, ...) noreturn
...
The noreturn attribute is set simply by:
  if (sym->ctype.modifiers & MOD_NORETURN)
      LLVMAddFunctionAttr(func, LLVMNoReturnAttribute);

Yep. I use the same test, but sym->ctype.modifiers is not set for me. The debug printf I added in handle_attributes() should have printed.

regards,
dan carpenter