From: Rameshwar Prasad Sahu <rsahu@apm.com>
Date: Thu, 2 Nov 2017 11:01:07 +0000 (+0530)
Subject: ata: fixes kernel crash while tracing ata_eh_link_autopsy event
X-Git-Tag: v4.4.103~68
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=189bc689547a57100cb0c5d0e689a8555e98b547;p=thirdparty%2Fkernel%2Fstable.git

ata: fixes kernel crash while tracing ata_eh_link_autopsy event

commit f1601113ddc0339a745e702f4fb1ca37d4875e65 upstream.

When tracing ata link error event, the kernel crashes when the disk is
removed due to NULL pointer access by trace_ata_eh_link_autopsy API.
This occurs as the dev is NULL when the disk disappeared. This patch
fixes this crash by calling trace_ata_eh_link_autopsy only if "dev"
is not NULL.

v2 changes:
 Removed direct passing "link" pointer instead of "dev" in trace API.

Signed-off-by: Rameshwar Prasad Sahu <rsahu@apm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 255c03d15a29 ("libata: Add tracepoints")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 91a9e6af2ec4d..75cced210b2a0 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2245,8 +2245,8 @@ static void ata_eh_link_autopsy(struct ata_link *link)
 		if (dev->flags & ATA_DFLAG_DUBIOUS_XFER)
 			eflags |= ATA_EFLAG_DUBIOUS_XFER;
 		ehc->i.action |= ata_eh_speed_down(dev, eflags, all_err_mask);
+		trace_ata_eh_link_autopsy(dev, ehc->i.action, all_err_mask);
 	}
-	trace_ata_eh_link_autopsy(dev, ehc->i.action, all_err_mask);
 	DPRINTK("EXIT\n");
 }