* Re: [PATCH] scsi: mvumi: fix 32 bit shift of a 32 bit unsigned int
@ 2019-02-16 16:27 Walter Harms
2019-02-18 9:37 ` Dan Carpenter
0 siblings, 1 reply; 5+ messages in thread
From: Walter Harms @ 2019-02-16 16:27 UTC (permalink / raw)
To: Colin King
Cc: Jianyun Li, James E . J . Bottomley, Martin K . Petersen,
linux-scsi, kernel-janitors, linux-kernel
Am 16.02.2019 15:44, schrieb Colin King:
> From: Colin Ian King <colin.king@canonical.com>
>
> Currently m_sg->baseaddr_h (a 32 bit unsigned int) is being shifted by a
> total of 32 bits; this always produces a 0 result. Fix this by casting
> it to a dma_addr_t (a 64 bit unsigned int) before performing the shift.
>
> Detected by CoverityScan, CID#147270 ("Operands don't affect result")
>
> Fixes: f0c568a478f0 ("[SCSI] mvumi: Add Marvell UMI driver")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
> drivers/scsi/mvumi.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/mvumi.c b/drivers/scsi/mvumi.c
> index 36f64205ecfa..d3582accfd09 100644
> --- a/drivers/scsi/mvumi.c
> +++ b/drivers/scsi/mvumi.c
> @@ -313,7 +313,7 @@ static void mvumi_delete_internal_cmd(struct mvumi_hba
> *mhba,
> sgd_getsz(mhba, m_sg, size);
>
> phy_addr = (dma_addr_t) m_sg->baseaddr_l |
> - (dma_addr_t) ((m_sg->baseaddr_h << 16) << 16);
> + (((dma_addr_t) m_sg->baseaddr_h << 16) << 16);
>
> dma_free_coherent(&mhba->pdev->dev, size, cmd->data_buf,
> phy_addr);
i would suggest to try a version with less casts to make it more readable
like this untested suggestion:
phy_addr =(m_sg->baseaddr_h << 16)| m_sg->baseaddr_l;
phy_addr <<= 16;
just my 2 cents,
re,
wh
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] scsi: mvumi: fix 32 bit shift of a 32 bit unsigned int
2019-02-16 16:27 [PATCH] scsi: mvumi: fix 32 bit shift of a 32 bit unsigned int Walter Harms
@ 2019-02-18 9:37 ` Dan Carpenter
2019-02-18 15:32 ` James Bottomley
0 siblings, 1 reply; 5+ messages in thread
From: Dan Carpenter @ 2019-02-18 9:37 UTC (permalink / raw)
To: Walter Harms
Cc: Colin King, Jianyun Li, James E . J . Bottomley,
Martin K . Petersen, linux-scsi, kernel-janitors, linux-kernel
On Sat, Feb 16, 2019 at 05:27:16PM +0100, Walter Harms wrote:
> Am 16.02.2019 15:44, schrieb Colin King:
> > From: Colin Ian King <colin.king@canonical.com>
> >
> > Currently m_sg->baseaddr_h (a 32 bit unsigned int) is being shifted by a
> > total of 32 bits; this always produces a 0 result. Fix this by casting
> > it to a dma_addr_t (a 64 bit unsigned int) before performing the shift.
> >
> > Detected by CoverityScan, CID#147270 ("Operands don't affect result")
> >
> > Fixes: f0c568a478f0 ("[SCSI] mvumi: Add Marvell UMI driver")
> > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> > ---
> > drivers/scsi/mvumi.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/scsi/mvumi.c b/drivers/scsi/mvumi.c
> > index 36f64205ecfa..d3582accfd09 100644
> > --- a/drivers/scsi/mvumi.c
> > +++ b/drivers/scsi/mvumi.c
> > @@ -313,7 +313,7 @@ static void mvumi_delete_internal_cmd(struct mvumi_hba
> > *mhba,
> > sgd_getsz(mhba, m_sg, size);
> >
> > phy_addr = (dma_addr_t) m_sg->baseaddr_l |
> > - (dma_addr_t) ((m_sg->baseaddr_h << 16) << 16);
> > + (((dma_addr_t) m_sg->baseaddr_h << 16) << 16);
> >
> > dma_free_coherent(&mhba->pdev->dev, size, cmd->data_buf,
> > phy_addr);
>
> i would suggest to try a version with less casts to make it more readable
> like this untested suggestion:
>
> phy_addr =(m_sg->baseaddr_h << 16)| m_sg->baseaddr_l;
> phy_addr <<= 16;
>
That would be a behavior change but it also might be a bugfix? Why
doesn't the code just do:
phy_addr = ((dma_addr_t)m_sg->baseaddr_h << 32) | m_sg->baseaddr_l;
(Probably they broke it up into two shifts to silence a GCC warning that
the shift was wrong because of the missing cast?)
regards,
dan carpenter
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] scsi: mvumi: fix 32 bit shift of a 32 bit unsigned int
2019-02-18 9:37 ` Dan Carpenter
@ 2019-02-18 15:32 ` James Bottomley
2019-02-18 15:47 ` Dan Carpenter
0 siblings, 1 reply; 5+ messages in thread
From: James Bottomley @ 2019-02-18 15:32 UTC (permalink / raw)
To: Dan Carpenter, Walter Harms
Cc: Colin King, Jianyun Li, Martin K . Petersen, linux-scsi,
kernel-janitors, linux-kernel
On Mon, 2019-02-18 at 12:37 +0300, Dan Carpenter wrote:
> On Sat, Feb 16, 2019 at 05:27:16PM +0100, Walter Harms wrote:
> > Am 16.02.2019 15:44, schrieb Colin King:
> > > From: Colin Ian King <colin.king@canonical.com>
> > >
> > > Currently m_sg->baseaddr_h (a 32 bit unsigned int) is being
> > > shifted by a
> > > total of 32 bits; this always produces a 0 result. Fix this by
> > > casting
> > > it to a dma_addr_t (a 64 bit unsigned int) before performing the
> > > shift.
> > >
> > > Detected by CoverityScan, CID#147270 ("Operands don't affect
> > > result")
> > >
> > > Fixes: f0c568a478f0 ("[SCSI] mvumi: Add Marvell UMI driver")
> > > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> > > ---
> > > drivers/scsi/mvumi.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/scsi/mvumi.c b/drivers/scsi/mvumi.c
> > > index 36f64205ecfa..d3582accfd09 100644
> > > --- a/drivers/scsi/mvumi.c
> > > +++ b/drivers/scsi/mvumi.c
> > > @@ -313,7 +313,7 @@ static void mvumi_delete_internal_cmd(struct
> > > mvumi_hba
> > > *mhba,
> > > sgd_getsz(mhba, m_sg, size);
> > >
> > > phy_addr = (dma_addr_t) m_sg->baseaddr_l
> > > |
> > > - (dma_addr_t) ((m_sg->baseaddr_h
> > > << 16) << 16);
> > > + (((dma_addr_t) m_sg->baseaddr_h
> > > << 16) << 16);
> > >
> > > dma_free_coherent(&mhba->pdev->dev,
> > > size, cmd->data_buf,
> > >
> > > phy_addr);
> >
> > i would suggest to try a version with less casts to make it more
> > readable
> > like this untested suggestion:
> >
> > phy_addr =(m_sg->baseaddr_h << 16)| m_sg->baseaddr_l;
> > phy_addr <<= 16;
> >
>
> That would be a behavior change but it also might be a bugfix? Why
> doesn't the code just do:
>
> phy_addr = ((dma_addr_t)m_sg->baseaddr_h << 32) | m_sg-
> >baseaddr_l;
>
> (Probably they broke it up into two shifts to silence a GCC warning
> that the shift was wrong because of the missing cast?)
No because dma_addr_t can be 32 bits and the warning would then always
appear on some builds. The << 16 << 16 makes sure it doesn't.
James
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] scsi: mvumi: fix 32 bit shift of a 32 bit unsigned int
2019-02-18 15:32 ` James Bottomley
@ 2019-02-18 15:47 ` Dan Carpenter
0 siblings, 0 replies; 5+ messages in thread
From: Dan Carpenter @ 2019-02-18 15:47 UTC (permalink / raw)
To: James Bottomley
Cc: Walter Harms, Colin King, Jianyun Li, Martin K . Petersen,
linux-scsi, kernel-janitors, linux-kernel
On Mon, Feb 18, 2019 at 07:32:05AM -0800, James Bottomley wrote:
> On Mon, 2019-02-18 at 12:37 +0300, Dan Carpenter wrote:
> > On Sat, Feb 16, 2019 at 05:27:16PM +0100, Walter Harms wrote:
> > > Am 16.02.2019 15:44, schrieb Colin King:
> > > > From: Colin Ian King <colin.king@canonical.com>
> > > >
> > > > Currently m_sg->baseaddr_h (a 32 bit unsigned int) is being
> > > > shifted by a
> > > > total of 32 bits; this always produces a 0 result. Fix this by
> > > > casting
> > > > it to a dma_addr_t (a 64 bit unsigned int) before performing the
> > > > shift.
> > > >
> > > > Detected by CoverityScan, CID#147270 ("Operands don't affect
> > > > result")
> > > >
> > > > Fixes: f0c568a478f0 ("[SCSI] mvumi: Add Marvell UMI driver")
> > > > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> > > > ---
> > > > drivers/scsi/mvumi.c | 2 +-
> > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/scsi/mvumi.c b/drivers/scsi/mvumi.c
> > > > index 36f64205ecfa..d3582accfd09 100644
> > > > --- a/drivers/scsi/mvumi.c
> > > > +++ b/drivers/scsi/mvumi.c
> > > > @@ -313,7 +313,7 @@ static void mvumi_delete_internal_cmd(struct
> > > > mvumi_hba
> > > > *mhba,
> > > > sgd_getsz(mhba, m_sg, size);
> > > >
> > > > phy_addr = (dma_addr_t) m_sg->baseaddr_l
> > > > |
> > > > - (dma_addr_t) ((m_sg->baseaddr_h
> > > > << 16) << 16);
> > > > + (((dma_addr_t) m_sg->baseaddr_h
> > > > << 16) << 16);
> > > >
> > > > dma_free_coherent(&mhba->pdev->dev,
> > > > size, cmd->data_buf,
> > > >
> > > > phy_addr);
> > >
> > > i would suggest to try a version with less casts to make it more
> > > readable
> > > like this untested suggestion:
> > >
> > > phy_addr =(m_sg->baseaddr_h << 16)| m_sg->baseaddr_l;
> > > phy_addr <<= 16;
> > >
> >
> > That would be a behavior change but it also might be a bugfix? Why
> > doesn't the code just do:
> >
> > phy_addr = ((dma_addr_t)m_sg->baseaddr_h << 32) | m_sg-
> > >baseaddr_l;
> >
> > (Probably they broke it up into two shifts to silence a GCC warning
> > that the shift was wrong because of the missing cast?)
>
> No because dma_addr_t can be 32 bits and the warning would then always
> appear on some builds. The << 16 << 16 makes sure it doesn't.
>
Yeah. You're right. Thanks.
The original patch is the right fix. Although it sort of feels like the
double shift should be a macro.
/*
* The dma_addr_t type can be either 32 or 64 bit. Left shifting a 32
* bit number is undefined so this do two 16 bit left shifts.
*
*/
#define DMA_LSHIFT_32(val) (((dma_addr_t)(val) << 16) << 16)
regards,
dan carpenter
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] scsi: mvumi: fix 32 bit shift of a 32 bit unsigned int
@ 2019-02-16 14:44 Colin King
0 siblings, 0 replies; 5+ messages in thread
From: Colin King @ 2019-02-16 14:44 UTC (permalink / raw)
To: Jianyun Li, James E . J . Bottomley, Martin K . Petersen, linux-scsi
Cc: kernel-janitors, linux-kernel
From: Colin Ian King <colin.king@canonical.com>
Currently m_sg->baseaddr_h (a 32 bit unsigned int) is being shifted by a
total of 32 bits; this always produces a 0 result. Fix this by casting
it to a dma_addr_t (a 64 bit unsigned int) before performing the shift.
Detected by CoverityScan, CID#147270 ("Operands don't affect result")
Fixes: f0c568a478f0 ("[SCSI] mvumi: Add Marvell UMI driver")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
drivers/scsi/mvumi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/scsi/mvumi.c b/drivers/scsi/mvumi.c
index 36f64205ecfa..d3582accfd09 100644
--- a/drivers/scsi/mvumi.c
+++ b/drivers/scsi/mvumi.c
@@ -313,7 +313,7 @@ static void mvumi_delete_internal_cmd(struct mvumi_hba *mhba,
sgd_getsz(mhba, m_sg, size);
phy_addr = (dma_addr_t) m_sg->baseaddr_l |
- (dma_addr_t) ((m_sg->baseaddr_h << 16) << 16);
+ (((dma_addr_t) m_sg->baseaddr_h << 16) << 16);
dma_free_coherent(&mhba->pdev->dev, size, cmd->data_buf,
phy_addr);
--
2.20.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
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2019-02-16 16:27 [PATCH] scsi: mvumi: fix 32 bit shift of a 32 bit unsigned int Walter Harms
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2019-02-18 15:47 ` Dan Carpenter
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