Re: [PATCH] ALSA: rme9652: Fix potential Spectre v1 vulnerability

[Takashi Iwai]

On Tue, 18 Dec 2018 18:18:34 +0100,
 Gustavo A. R. Silva  wrote:
> 
> info->channel is indirectly controlled by user-space, hence leading to
> a potential exploitation of the Spectre variant 1 vulnerability.
> 
> This issue was detected with the help of Smatch:
> 
> sound/pci/rme9652/hdsp.c:4100 snd_hdsp_channel_info() warn: potential spectre issue 'hdsp->channel_map' [r] (local cap)
> 
> Fix this by sanitizing info->channel before using it to index hdsp->channel_map
> 
> Notice that given that speculation windows are large, the policy is
> to kill the speculation on the first load and not worry if it can be
> completed with a dependent load/store [1].
> 
> Also, notice that I refactored the code a bit in order to get rid of the
> following checkpatch warning:
> 
> ERROR: do not use assignment in if condition
> FILE: sound/pci/rme9652/hdsp.c:4103:
> 	if ((mapped_channel = hdsp->channel_map[info->channel]) < 0)
> 
> 
> [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>

Applied, thanks.


Takashi