ALSA: pcm: Fix potential Spectre v1 vulnerability

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commit 94ffb030b6 upstream.

stream 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/core/pcm.c:140 snd_pcm_control_ioctl() warn: potential spectre issue 'pcm->streams' [r] (local cap)

Fix this by sanitizing stream before using it to index pcm->streams

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].

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

...

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Gustavo A. R. Silva 2018-12-12 15:36:28 -06:00 • committed by Ben Hutchings

parent 913fc5d772

commit b2bf1147c2

1 changed files with 2 additions and 0 deletions

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sound/core/pcm.c

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