[PATCH] drm/amdgpu: Handle potential NULL pointer dereference

[Kent Russell]

If m is NULL, we will end up referencing a NULL pointer in the
subsequent m elements like extcpu, bank and status. Pull the NULL
check out and do it first before referencing m's elements.

Signed-off-by: Kent Russell <kent.russell at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
index ab9ba5a9c33d..028495fdfa62 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
@@ -2838,12 +2838,15 @@ static int amdgpu_bad_page_notifier(struct notifier_block *nb,
 	struct eeprom_table_record err_rec;
 	uint64_t retired_page;
 
+	if (!m)
+		return NOTIFY_DONE;
+
 	/*
 	 * If the error was generated in UMC_V2, which belongs to GPU UMCs,
 	 * and error occurred in DramECC (Extended error code = 0) then only
 	 * process the error, else bail out.
 	 */
-	if (!m || !((smca_get_bank_type(m->extcpu, m->bank) == SMCA_UMC_V2) &&
+	if (!((smca_get_bank_type(m->extcpu, m->bank) == SMCA_UMC_V2) &&
 		    (XEC(m->status, 0x3f) == 0x0)))
 		return NOTIFY_DONE;
 
-- 
2.25.1