Re: [PATCH] ufs: free the buffer head container in ubh_bforget

[Luis Henriques]

On Sat, Aug 01 2026, Ali Ahmet Memis wrote:

> ubh_bforget() forgets the buffer heads referenced by a struct
> ufs_buffer_head but never frees the container itself, unlike its
> sibling ubh_brelse() which calls kfree() on the way out. The only
> caller, free_full_branch(), allocates the container through ubh_bread()
> while releasing an indirect block during truncate, so every fully
> removed indirect block leaks one ufs_buffer_head. Truncating or
> unlinking a large file then leaks one allocation per indirect block,
> which kmemleak reports with a free_full_branch, ufs_truncate_blocks,
> ufs_evict_inode backtrace.
>
> Free the container after forgetting its buffers, mirroring ubh_brelse().
>
> Luis Henriques posted a fix for this leak in 2018, but it was never
> applied while fs/ufs had no active maintainer, and the leak is still
> present.

It's been a while, and I don't even remember why I was running xfstests
against this filesystem :-)

But the fix still looks OK.  My original patch also dropped the 'if', but
that's just a minor detail.  I don't know who's using this ufs driver
these days -- each BSD has it's own thing, and it's likely to be risky to
mount a filesystem in rw mode.

Cheers,
-- 
Luís


> Link: https://lore.kernel.org/all/20180705150415.25070-1-lhenriques@xxxxxxxx/
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Ali Ahmet Memis <ali@xxxxxxxxxxxxxx>
> ---
>  fs/ufs/util.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ufs/util.c b/fs/ufs/util.c
> index dff6f7461..3c65fbef6 100644
> --- a/fs/ufs/util.c
> +++ b/fs/ufs/util.c
> @@ -117,8 +117,10 @@ void ubh_bforget (struct ufs_buffer_head * ubh)
>  	unsigned i;
>  	if (!ubh) 
>  		return;
> -	for ( i = 0; i < ubh->count; i++ ) if ( ubh->bh[i] ) 
> -		bforget (ubh->bh[i]);
> +	for (i = 0; i < ubh->count; i++)
> +		if (ubh->bh[i])
> +			bforget(ubh->bh[i]);
> +	kfree(ubh);
>  }
>   
>  int ubh_buffer_dirty (struct ufs_buffer_head * ubh)
> -- 
> 2.54.0
>