linux-kernel - Re: [Patch 3/9] fs/compat.c: fix resource leaks and wrong goto's

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Message-ID: <20080510203543.GJ13907@ZenIV.linux.org.uk>
Date:	Sat, 10 May 2008 21:35:43 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	WANG Cong <xiyou.wangcong@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...l.org>,
	WANG Cong <wangcong@...ux.org>
Subject: Re: [Patch 3/9] fs/compat.c: fix resource leaks and wrong goto's

On Sat, May 10, 2008 at 08:21:11PM +0100, Al Viro wrote:
> On Thu, May 08, 2008 at 09:52:28PM +0800, WANG Cong wrote:
> > Use free_arg_pages() to free the pages allocated by copy_strings_kernel()
> > on failure. And fix some related wrong goto pathes.
> 
> Kinda; free_arg_pages() is needed here, but there's no need to mess with
> goto - just put it under out:
> 
> Note that it's essentially just a part of freeing bprm; it's _not_ a "clean
> collected strings, so that we could add new ones".

FWIW, I'd suggest this:

diff --git a/fs/compat.c b/fs/compat.c
index 332a869..ed43e17 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1405,7 +1405,7 @@ int compat_do_execve(char * filename,
 		/* execve success */
 		security_bprm_free(bprm);
 		acct_update_integrals(current);
-		kfree(bprm);
+		free_bprm(bprm);
 		return retval;
 	}
 
@@ -1424,7 +1424,7 @@ out_file:
 	}
 
 out_kfree:
-	kfree(bprm);
+	free_bprm(bprm);
 
 out_ret:
 	return retval;
diff --git a/fs/exec.c b/fs/exec.c
index aeaa979..ad545b0 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1251,6 +1251,12 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 
 EXPORT_SYMBOL(search_binary_handler);
 
+void free_bprm(struct linux_binprm *bprm)
+{
+	free_arg_pages(bprm);
+	kfree(bprm);
+}
+
 /*
  * sys_execve() executes a new program.
  */
@@ -1320,17 +1326,15 @@ int do_execve(char * filename,
 	retval = search_binary_handler(bprm,regs);
 	if (retval >= 0) {
 		/* execve success */
-		free_arg_pages(bprm);
 		security_bprm_free(bprm);
 		acct_update_integrals(current);
-		kfree(bprm);
+		free_bprm(bprm);
 		if (displaced)
 			put_files_struct(displaced);
 		return retval;
 	}
 
 out:
-	free_arg_pages(bprm);
 	if (bprm->security)
 		security_bprm_free(bprm);
 
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index b512e48..c2f7fba 100644
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -99,6 +99,7 @@ extern int copy_strings_kernel(int argc,char ** argv,struct linux_binprm *bprm);
 extern void compute_creds(struct linux_binprm *binprm);
 extern int do_coredump(long signr, int exit_code, struct pt_regs * regs);
 extern int set_binfmt(struct linux_binfmt *new);
+extern void free_bprm(struct linux_binfmt *);
 
 #endif /* __KERNEL__ */
 #endif /* _LINUX_BINFMTS_H */
--
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