From b972fdba8665d75109ade0357739f46af6415d2a Mon Sep 17 00:00:00 2001
From: Shiju Jose <shiju.jose@huawei.com>
Date: Thu, 27 Aug 2020 15:04:50 +0100
Subject: EDAC/ghes: Fix NULL pointer dereference in ghes_edac_register()
After
b9cae27728d1 ("EDAC/ghes: Scan the system once on driver init")
and with CONFIG_DEBUG_TEST_DRIVER_REMOVE enabled, ghes_hw.dimms becomes
a NULL pointer after the second ->probe() (aka ghes_edac_register())
which the config option causes to be called.
This happens because the static variable which holds down whether
the system has been scanned already, doesn't get reset in
ghes_edac_unregister(). Then, on the second probe, ghes_scan_system()
doesn't get to enumerate the DIMMs, leading to ghes_hw.dimms remaining
NULL.
Clear the variable and rename it to something more descriptive so that a
second probe succeeds.
[ bp: Rewrite commit message. ]
Fixes: b9cae27728d1 ("EDAC/ghes: Scan the system once on driver init")
Suggested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200827140450.1620-1-shiju.jose@huawei.com
---
drivers/edac/ghes_edac.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
(limited to 'drivers/edac/ghes_edac.c')
diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c
index da60c29468a7..54ebc8afc6b1 100644
--- a/drivers/edac/ghes_edac.c
+++ b/drivers/edac/ghes_edac.c
@@ -55,6 +55,8 @@ static DEFINE_SPINLOCK(ghes_lock);
static bool __read_mostly force_load;
module_param(force_load, bool, 0);
+static bool system_scanned;
+
/* Memory Device - Type 17 of SMBIOS spec */
struct memdev_dmi_entry {
u8 type;
@@ -225,14 +227,12 @@ static void enumerate_dimms(const struct dmi_header *dh, void *arg)
static void ghes_scan_system(void)
{
- static bool scanned;
-
- if (scanned)
+ if (system_scanned)
return;
dmi_walk(enumerate_dimms, &ghes_hw);
- scanned = true;
+ system_scanned = true;
}
void ghes_edac_report_mem_error(int sev, struct cper_sec_mem_err *mem_err)
@@ -631,6 +631,8 @@ void ghes_edac_unregister(struct ghes *ghes)
mutex_lock(&ghes_reg_mutex);
+ system_scanned = false;
+
if (!refcount_dec_and_test(&ghes_refcount))
goto unlock;
--
cgit