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From: Andrew Lutomirski <luto@mit.edu>
Date: Thu, 25 Feb 2010 15:48:21 -0500
Message-ID: <cb0375e11002251248h17f46468x9a5c3bab0e8bf60d@mail.gmail.com>
Subject: Re: [2.6.33 regression] btrfs mount causes memory corruption
To: Josef Bacik <josef@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org
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On Thu, Feb 25, 2010 at 3:38 PM, Josef Bacik <josef@redhat.com> wrote:
>
> Ok it looks like we have a problem kfree'ing the wrong stuff. ?we kstrdup the
> options string, but then strsep screws with the pointer, so when we kfree() it,
> we're not giving it the right pointer. ?Please try this patch, and mount with -o
> acl and other such garbage to make sure it actually worked (acl isn't a valid
> mount option btw). ?Let me know if it works. ?Thanks,
>
> Josef
>
>
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 8a1ea6e..f8b4521 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -128,7 +128,7 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
> ?{
> ? ? ? ?struct btrfs_fs_info *info = root->fs_info;
> ? ? ? ?substring_t args[MAX_OPT_ARGS];
> - ? ? ? char *p, *num;
> + ? ? ? char *p, *num, *orig;
> ? ? ? ?int intarg;
> ? ? ? ?int ret = 0;
>
> @@ -143,6 +143,7 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
> ? ? ? ?if (!options)
> ? ? ? ? ? ? ? ?return -ENOMEM;
>
> + ? ? ? orig = options;
>
> ? ? ? ?while ((p = strsep(&options, ",")) != NULL) {
> ? ? ? ? ? ? ? ?int token;
> @@ -280,7 +281,7 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
> ? ? ? ? ? ? ? ?}
> ? ? ? ?}
> ?out:
> - ? ? ? kfree(options);
> + ? ? ? kfree(orig);
> ? ? ? ?return ret;
> ?}
>
>


Thanks for the instant patch.  I hammered on it a bit and it hasn't
crashed yet.  I'll let you know if it crashes later.  (The earlier
trial with xattr crashed after a couple minutes.)

In the mean time,

Tested-by: Andy Lutomirski <luto@mit.edu>

--Andy
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