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* [PATCH] isci: Fix infinite loop in while loop
@ 2018-04-20  9:03 Colin King
  2018-04-20  9:45 ` James Bottomley
  0 siblings, 1 reply; 3+ messages in thread
From: Colin King @ 2018-04-20  9:03 UTC (permalink / raw)
  To: Intel SCU Linux support, Artur Paszkiewicz,
	James E . J . Bottomley, Martin K . Petersen, linux-scsi
  Cc: kernel-janitors, linux-kernel

From: Colin Ian King <colin.king@canonical.com>

In the case when the phy_mask is bitwise anded with the
phy_index bit is zero the continue statement currently jumps
to the next iteration of the while loop and phy_index is
never actually incremented, potentially causing an infinite
loop if phy_index is less than SCI_MAX_PHS. Fix this by
jumping to the increment of phy_index.

[ The goto is used to save one more level of nesting that
makes the code far wider than 80 columns. ]

Fixes: 80aebef7c112 ("[SCSI] isci: Fix a infinite loop.")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/scsi/isci/port_config.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/isci/port_config.c b/drivers/scsi/isci/port_config.c
index edb7be786c65..55dc7c1dbc2b 100644
--- a/drivers/scsi/isci/port_config.c
+++ b/drivers/scsi/isci/port_config.c
@@ -293,7 +293,7 @@ sci_mpc_agent_validate_phy_configuration(struct isci_host *ihost,
 		 *       This is expected and required to add the phy to the port. */
 		while (phy_index < SCI_MAX_PHYS) {
 			if ((phy_mask & (1 << phy_index)) == 0)
-				continue;
+				goto next_index;
 			sci_phy_get_sas_address(&ihost->phys[phy_index],
 						     &phy_assigned_address);
 
@@ -311,6 +311,7 @@ sci_mpc_agent_validate_phy_configuration(struct isci_host *ihost,
 					      &ihost->phys[phy_index]);
 
 			assigned_phy_mask |= (1 << phy_index);
+next_index:
 			phy_index++;
 		}
 
-- 
2.17.0

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] isci: Fix infinite loop in while loop
  2018-04-20  9:03 [PATCH] isci: Fix infinite loop in while loop Colin King
@ 2018-04-20  9:45 ` James Bottomley
  2018-04-20  9:57   ` Colin Ian King
  0 siblings, 1 reply; 3+ messages in thread
From: James Bottomley @ 2018-04-20  9:45 UTC (permalink / raw)
  To: Colin King, Intel SCU Linux support, Artur Paszkiewicz,
	Martin K . Petersen, linux-scsi
  Cc: kernel-janitors, linux-kernel

On Fri, 2018-04-20 at 10:03 +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> In the case when the phy_mask is bitwise anded with the
> phy_index bit is zero the continue statement currently jumps
> to the next iteration of the while loop and phy_index is
> never actually incremented, potentially causing an infinite
> loop if phy_index is less than SCI_MAX_PHS. Fix this by
> jumping to the increment of phy_index.
> 
> [ The goto is used to save one more level of nesting that
> makes the code far wider than 80 columns. ]

what's wrong with replacing the while() with a for() that just works
(removing the increment at the end).  This is effectively open coding a
for loop anyway, which is a pattern we wouldn't want replicated.

James

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] isci: Fix infinite loop in while loop
  2018-04-20  9:45 ` James Bottomley
@ 2018-04-20  9:57   ` Colin Ian King
  0 siblings, 0 replies; 3+ messages in thread
From: Colin Ian King @ 2018-04-20  9:57 UTC (permalink / raw)
  To: James Bottomley, Intel SCU Linux support, Artur Paszkiewicz,
	Martin K . Petersen, linux-scsi
  Cc: kernel-janitors, linux-kernel

On 20/04/18 10:45, James Bottomley wrote:
> On Fri, 2018-04-20 at 10:03 +0100, Colin King wrote:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> In the case when the phy_mask is bitwise anded with the
>> phy_index bit is zero the continue statement currently jumps
>> to the next iteration of the while loop and phy_index is
>> never actually incremented, potentially causing an infinite
>> loop if phy_index is less than SCI_MAX_PHS. Fix this by
>> jumping to the increment of phy_index.
>>
>> [ The goto is used to save one more level of nesting that
>> makes the code far wider than 80 columns. ]
> 
> what's wrong with replacing the while() with a for() that just works
> (removing the increment at the end).  This is effectively open coding a
> for loop anyway, which is a pattern we wouldn't want replicated.
> 
> James
> 
Good point, V2 en-route.

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2018-04-20  9:57 UTC | newest]

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2018-04-20  9:03 [PATCH] isci: Fix infinite loop in while loop Colin King
2018-04-20  9:45 ` James Bottomley
2018-04-20  9:57   ` Colin Ian King

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