[PATCH 4.4 30/96] ata: fixes kernel crash while tracing ata_eh_link_autopsy event

Greg Kroah-Hartman
2017-11-28T10:28:43Z

From: Rameshwar Prasad Sahu <rsahu@apm.com>

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>

---
drivers/ata/libata-eh.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2245,8 +2245,8 @@ static void ata_eh_link_autopsy(struct a
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");
}