linux-kernel - Re: [PATCH] Check return from argv_split() in do

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Date:	Fri, 26 Dec 2008 22:20:09 +0900
From:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:	xiyou.wangcong@...il.com
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org
Subject: Re: [PATCH] Check return from argv_split() in do_coredump().

Hello.

Americo Wang wrote:
> fail_unlock:
>         if (helper_argv)
> 	                argv_free(helper_argv);
> 
>         current->fsuid = fsuid; //<=== goto this line
>         coredump_finish(mm);
> 
> You need to add a new label, of course. :)
> 
Ah, you were talking about destination of goto statement. I see.

Unfortunately, -mm source uses "revert_creds(old_cred); put_cred(cred);"
instead of "current->fsuid = fsuid;".
To keep this patch applicable to all afftected versions,
I'd like not to introduce a new label.

> if (helper_argv)
> 	                argv_free(helper_argv);
Well, I think it's better to check "if (helper_argv)" inside argv_free()
in case the caller forgets to check.

Regards.
--------------------
Subject: Check return from argv_split() in do_coredump().

do_coredump() accesses helper_argv[0] without checking helper_argv != NULL.
Though, likely helper_argv != NULL.

Below versions have this problem.

  2.6.24.7
  2.6.25.20
  2.6.26.8
  2.6.27.10
  2.6.28
  mmotm 2008-12-24-01-20

Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
---
 fs/exec.c |    2 ++
 1 file changed, 2 insertions(+)

--- linux-2.6.28-rc9-mm1.orig/fs/exec.c
+++ linux-2.6.28-rc9-mm1/fs/exec.c
@@ -1808,6 +1808,8 @@ int do_coredump(long signr, int exit_cod
 
  	if (ispipe) {
 		helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
+		if (!helper_argv)
+			goto fail_unlock;
 		/* Terminate the string before the first option */
 		delimit = strchr(corename, ' ');
 		if (delimit)
--
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