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ALSA: pcm: Add sanity NULL check for the default mmap fault handler

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commit d2913a07d9 upstream.

A driver might allow the mmap access before initializing its
runtime->dma_area properly.  Add a proper NULL check before passing to
virt_to_page() for avoiding a panic.

Reported-by: syzbot+4bf62a7b1d0f4fdb7ae2@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Link: https://patch.msgid.link/20241120141104.7060-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Takashi Iwai 2024-11-20 15:11:02 +01:00 committed by Greg Kroah-Hartman
parent 71f9c0f1e3
commit 832efbb74b
1 changed files with 4 additions and 2 deletions
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6
sound/core/pcm_native.c
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@ -3785,9 +3785,11 @@ static vm_fault_t snd_pcm_mmap_data_fault(struct vm_fault *vmf)
return VM_FAULT_SIGBUS;
if (substream->ops->page)
page = substream->ops->page(substream, offset);
else if (!snd_pcm_get_dma_buf(substream))
else if (!snd_pcm_get_dma_buf(substream)) {
if (WARN_ON_ONCE(!runtime->dma_area))
return VM_FAULT_SIGBUS;
page = virt_to_page(runtime->dma_area + offset);
else
} else
page = snd_sgbuf_get_page(snd_pcm_get_dma_buf(substream), offset);
if (!page)
return VM_FAULT_SIGBUS;