linux-kernel - [PATCH] libata: add missing NULL pointer check to ata_eh

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Message-Id: <200907261621.01893.bzolnier@gmail.com>
Date:	Sun, 26 Jul 2009 16:21:01 +0200
From:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
To:	jgarzik@...ox.com
Cc:	linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org,
	Dan Carpenter <error27@...il.com>, corbet@....net,
	eteo@...hat.com
Subject: [PATCH] libata: add missing NULL pointer check to ata_eh_reset()

From: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
Subject: [PATCH] libata: add missing NULL pointer check to ata_eh_reset()

>From Dan's list:

drivers/ata/libata-eh.c +2403 ata_eh_reset(80) warning: variable derefenced before check 'slave'

Please note that this is _not_ a real bug at the moment since ata_eh_context
structure is embedded into ata_list structure and the code alwas checks for
'slave' before accessing 'sehc'.

Anyway lets add missing check and always have a valid 'sehc' pointer (which
makes code easier to understand and prevents introducing some possible bugs
in the future).

Reported-by: Dan Carpenter <error27@...il.com>
Cc: corbet@....net
Cc: eteo@...hat.com
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
---
 drivers/ata/libata-eh.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: b/drivers/ata/libata-eh.c
===================================================================
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2329,7 +2329,7 @@ int ata_eh_reset(struct ata_link *link, 
 	struct ata_port *ap = link->ap;
 	struct ata_link *slave = ap->slave_link;
 	struct ata_eh_context *ehc = &link->eh_context;
-	struct ata_eh_context *sehc = &slave->eh_context;
+	struct ata_eh_context *sehc = slave ? &slave->eh_context : NULL;
 	unsigned int *classes = ehc->classes;
 	unsigned int lflags = link->flags;
 	int verbose = !(ehc->i.flags & ATA_EHI_QUIET);
--
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