Re: [PATCH] ALSA: hda/core: fix memory leak in snd_hdac_bus_alloc_stream_pages()

[Takashi Iwai]

On Mon, 06 Jul 2026 09:41:10 +0200,
Zhao Dongdong wrote:
> 
> From: Zhao Dongdong <zhaodongdong@xxxxxxxxxx>
> 
> In snd_hdac_bus_alloc_stream_pages(), there are three memory leak paths:
> 
>   1. If snd_dma_alloc_pages() for the BDL fails at stream i, the
>      previously allocated BDL DMA buffers (0..i-1) are not freed.
> 
>   2. If snd_dma_alloc_pages() for the position buffer fails, all
>      previously allocated BDL DMA buffers are leaked.
> 
>   3. If snd_dma_alloc_pages() for the ring buffer fails, all
>      previously allocated BDL DMA buffers and the position buffer
>      are leaked.
> 
> Add proper error cleanup: free buffers that have been allocated
> before each failure point.
> 
> Fixes: b2660d1ebde1 ("ALSA: hda: Move HD-audio core stuff into sound/hda/core")
> Signed-off-by: Zhao Dongdong <zhaodongdong@xxxxxxxxxx>

They don't actually leak, as those are supposed to be released by
callers (via snd_hdac_bus_free_stream_pages() call at destructor).
That is, it's no bug, per se.

Of course, it won't be bad to clean up in the function itself, which
is more self-contained and safer.  But please rephrase the patch
subject and description, so that it won't be taken as a security issue
incorrectly.


thanks,

Takashi