Re: [Xen-devel] [PATCH] ALSA: xen-front: fix unintention integer overflow on left shifts

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On 6/28/19 11:46 AM, Takashi Iwai wrote:
On Thu, 27 Jun 2019 18:58:53 +0200,
Colin King wrote:
From: Colin Ian King <colin.king@xxxxxxxxxxxxx>

Shifting the integer value 1 is evaluated using 32-bit
arithmetic and then used in an expression that expects a 64-bit
value, so there is potentially an integer overflow. Fix this
by using the BIT_ULL macro to perform the shift.

Addresses-Coverity: ("Unintentional integer overflow")
Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
Thank you for you patch,
Oleksandr
The fix is correct, but luckily we didn't hit the integer overflow, as
all passed values are less than 32bit.

In anyway, applied now.  Thanks.


Takashi

---
  sound/xen/xen_snd_front_alsa.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/xen/xen_snd_front_alsa.c b/sound/xen/xen_snd_front_alsa.c
index b14ab512c2ce..e01631959ed8 100644
--- a/sound/xen/xen_snd_front_alsa.c
+++ b/sound/xen/xen_snd_front_alsa.c
@@ -196,7 +196,7 @@ static u64 to_sndif_formats_mask(u64 alsa_formats)
  	mask = 0;
  	for (i = 0; i < ARRAY_SIZE(ALSA_SNDIF_FORMATS); i++)
  		if (pcm_format_to_bits(ALSA_SNDIF_FORMATS[i].alsa) & alsa_formats)
-			mask |= 1 << ALSA_SNDIF_FORMATS[i].sndif;
+			mask |= BIT_ULL(ALSA_SNDIF_FORMATS[i].sndif);
return mask;
  }
@@ -208,7 +208,7 @@ static u64 to_alsa_formats_mask(u64 sndif_formats)
mask = 0;
  	for (i = 0; i < ARRAY_SIZE(ALSA_SNDIF_FORMATS); i++)
-		if (1 << ALSA_SNDIF_FORMATS[i].sndif & sndif_formats)
+		if (BIT_ULL(ALSA_SNDIF_FORMATS[i].sndif) & sndif_formats)
  			mask |= pcm_format_to_bits(ALSA_SNDIF_FORMATS[i].alsa);
return mask;
--
2.20.1


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