btrfs: qgroup: don't use extent changeset when not needed

[PATCH v2] btrfs: qgroup: don't use extent changeset when not needed

Posted by Fedor Pchelkin 1 year, 3 months ago

The local extent changeset is passed to clear_record_extent_bits() where
it may have some additional memory dynamically allocated for ulist. When
qgroup is disabled, the memory is leaked because in this case the
changeset is not released upon __btrfs_qgroup_release_data() return.

Since the recorded contents of the changeset are not used thereafter, just
don't pass it.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Reported-by: syzbot+81670362c283f3dd889c@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/lkml/000000000000aa8c0c060ade165e@google.com
Fixes: af0e2aab3b70 ("btrfs: qgroup: flush reservations during quota disable")
Cc: stable@vger.kernel.org # 6.10+
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
---
v2: rework the fix as Qu Wenruo suggested - just don't pass unneeded
    changeset. Update the commit title and description accordingly.

 fs/btrfs/qgroup.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 5d57a285d59b..f6118c5f3c9f 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -4344,10 +4344,9 @@ static int __btrfs_qgroup_release_data(struct btrfs_inode *inode,
 	int ret;
 
 	if (btrfs_qgroup_mode(inode->root->fs_info) == BTRFS_QGROUP_MODE_DISABLED) {
-		extent_changeset_init(&changeset);
 		return clear_record_extent_bits(&inode->io_tree, start,
 						start + len - 1,
-						EXTENT_QGROUP_RESERVED, &changeset);
+						EXTENT_QGROUP_RESERVED, NULL);
 	}
 
 	/* In release case, we shouldn't have @reserved */
-- 
2.39.2

Re: [PATCH v2] btrfs: qgroup: don't use extent changeset when not needed

Posted by David Sterba 1 year, 3 months ago

On Wed, Aug 28, 2024 at 07:14:11PM +0300, Fedor Pchelkin wrote:
> The local extent changeset is passed to clear_record_extent_bits() where
> it may have some additional memory dynamically allocated for ulist. When
> qgroup is disabled, the memory is leaked because in this case the
> changeset is not released upon __btrfs_qgroup_release_data() return.
> 
> Since the recorded contents of the changeset are not used thereafter, just
> don't pass it.
> 
> Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
> 
> Reported-by: syzbot+81670362c283f3dd889c@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/lkml/000000000000aa8c0c060ade165e@google.com
> Fixes: af0e2aab3b70 ("btrfs: qgroup: flush reservations during quota disable")
> Cc: stable@vger.kernel.org # 6.10+
> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
> ---
> v2: rework the fix as Qu Wenruo suggested - just don't pass unneeded
>     changeset. Update the commit title and description accordingly.

Thanks, added to for-next.

Re: [PATCH v2] btrfs: qgroup: don't use extent changeset when not needed

Posted by Qu Wenruo 1 year, 3 months ago


在 2024/8/29 01:44, Fedor Pchelkin 写道:
> The local extent changeset is passed to clear_record_extent_bits() where
> it may have some additional memory dynamically allocated for ulist. When
> qgroup is disabled, the memory is leaked because in this case the
> changeset is not released upon __btrfs_qgroup_release_data() return.
>
> Since the recorded contents of the changeset are not used thereafter, just
> don't pass it.
>
> Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
>
> Reported-by: syzbot+81670362c283f3dd889c@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/lkml/000000000000aa8c0c060ade165e@google.com
> Fixes: af0e2aab3b70 ("btrfs: qgroup: flush reservations during quota disable")
> Cc: stable@vger.kernel.org # 6.10+
> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>

Reviewed-by: Qu Wenruo <wqu@suse.com>

Thanks,
Qu

> ---
> v2: rework the fix as Qu Wenruo suggested - just don't pass unneeded
>      changeset. Update the commit title and description accordingly.
>
>   fs/btrfs/qgroup.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index 5d57a285d59b..f6118c5f3c9f 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -4344,10 +4344,9 @@ static int __btrfs_qgroup_release_data(struct btrfs_inode *inode,
>   	int ret;
>
>   	if (btrfs_qgroup_mode(inode->root->fs_info) == BTRFS_QGROUP_MODE_DISABLED) {
> -		extent_changeset_init(&changeset);
>   		return clear_record_extent_bits(&inode->io_tree, start,
>   						start + len - 1,
> -						EXTENT_QGROUP_RESERVED, &changeset);
> +						EXTENT_QGROUP_RESERVED, NULL);
>   	}
>
>   	/* In release case, we shouldn't have @reserved */

Re: [PATCH v2] btrfs: qgroup: don't use extent changeset when not needed

Posted by Boris Burkov 1 year, 3 months ago

On Wed, Aug 28, 2024 at 07:14:11PM +0300, Fedor Pchelkin wrote:
> The local extent changeset is passed to clear_record_extent_bits() where
> it may have some additional memory dynamically allocated for ulist. When
> qgroup is disabled, the memory is leaked because in this case the
> changeset is not released upon __btrfs_qgroup_release_data() return.
> 
> Since the recorded contents of the changeset are not used thereafter, just
> don't pass it.
> 
> Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
> 
> Reported-by: syzbot+81670362c283f3dd889c@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/lkml/000000000000aa8c0c060ade165e@google.com
> Fixes: af0e2aab3b70 ("btrfs: qgroup: flush reservations during quota disable")
> Cc: stable@vger.kernel.org # 6.10+
> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>

This version looks even better, to me. Thanks for the catch and fix!

Reviewed-by: Boris Burkov <boris@bur.io>

> ---
> v2: rework the fix as Qu Wenruo suggested - just don't pass unneeded
>     changeset. Update the commit title and description accordingly.
> 
>  fs/btrfs/qgroup.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index 5d57a285d59b..f6118c5f3c9f 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -4344,10 +4344,9 @@ static int __btrfs_qgroup_release_data(struct btrfs_inode *inode,
>  	int ret;
>  
>  	if (btrfs_qgroup_mode(inode->root->fs_info) == BTRFS_QGROUP_MODE_DISABLED) {
> -		extent_changeset_init(&changeset);
>  		return clear_record_extent_bits(&inode->io_tree, start,
>  						start + len - 1,
> -						EXTENT_QGROUP_RESERVED, &changeset);
> +						EXTENT_QGROUP_RESERVED, NULL);
>  	}
>  
>  	/* In release case, we shouldn't have @reserved */
> -- 
> 2.39.2
>