linux-ext4 - Re: [PATCH 21/25] e2fsck: Fix leaks in error paths

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Message-ID: <20110916234113.GY16246@thunk.org>
Date:	Fri, 16 Sep 2011 19:41:13 -0400
From:	Ted Ts'o <tytso@....edu>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 21/25] e2fsck: Fix leaks in error paths

On Fri, Sep 16, 2011 at 03:49:36PM -0500, Eric Sandeen wrote:
> fn and/or array was not freed in some error paths.
> 
> Signed-off-by: Eric Sandeen <sandeen@...hat.com>

Applied, but I did make a two changes.

> @@ -345,6 +346,7 @@ profile_init(const char **files, profile_t *ret_profile)
>  	     * If all the files were not found, return the appropriate error.
>  	     */
>  	    if (!profile->first_file) {
> +		free_list(array);
>  		profile_release(profile);
>  		return ENOENT;
>  	    }

I changed this to be:

 	    if (!profile->first_file) {
 		retval = ENOENT;
		goto errout;
 	    }

Which allows us to unify the error cleanup path and avoid duplicating
code.

Also, I noticed another bug while I was validating your patch.  If the
realloc() in get_dirlist() fails due to a ENOMEM, and we jump to
errout, the array hasn't been null terminated yet.  This could lead to
lead a kernel oops or worse when free_list(array) tries to free the
array.

So I added:

errout:
+	if (array)
+	   array[num] = 0;

to take care of this problem.

				- Ted

commit 04bfa75f42a5adb3510551f4d153526d94be37fb
Author: Eric Sandeen <sandeen@...hat.com>
Date:   Fri Sep 16 15:49:36 2011 -0500

    e2fsck: Fix leaks in error paths
    
    fn and/or array was not freed in some error paths.
    
    [ Also make sure the array is NULL terminated before we free it in
      get_dirlist(). --tytso]
    
    Signed-off-by: Eric Sandeen <sandeen@...hat.com>
    Signed-off-by: Theodore Ts'o <tytso@....edu>

diff --git a/e2fsck/profile.c b/e2fsck/profile.c
index 327bfb4..f4267b1 100644
--- a/e2fsck/profile.c
+++ b/e2fsck/profile.c
@@ -276,6 +276,7 @@ static errcode_t get_dirlist(const char *dirname, char***ret_array)
 			new_array = realloc(array, sizeof(char *) * (max+1));
 			if (!new_array) {
 				retval = ENOMEM;
+				free(fn);
 				goto errout;
 			}
 			array = new_array;
@@ -290,6 +291,8 @@ static errcode_t get_dirlist(const char *dirname, char***ret_array)
 	closedir(dir);
 	return 0;
 errout:
+	if (array)
+		array[num] = 0;
 	closedir(dir);
 	free_list(array);
 	return retval;
@@ -345,8 +348,8 @@ profile_init(const char **files, profile_t *ret_profile)
 	     * If all the files were not found, return the appropriate error.
 	     */
 	    if (!profile->first_file) {
-		profile_release(profile);
-		return ENOENT;
+		retval = ENOENT;
+		goto errout;
 	    }
 	}
 
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