Re: NULL pointer dereference in igen6_probe - 6.16-rc2

[Borislav Petkov]

On Tue, Jun 17, 2025 at 01:13:49PM +0200, Marek Marczykowski-Górecki wrote:
> [   13.562085] intel_pmc_core INT33A1:00: Assuming a default substate order for this platform
> [   13.562682] intel_pmc_core INT33A1:00:  initialized
> [   13.565035] EDAC MC0: Giving out device to module igen6_edac controller Intel_client_SoC MC#0: DEV 0000:00:00.0 (INTERRUPT)
> [   13.565746] EDAC igen6: Expected 2 mcs, but only 1 detected.

Well, folks, if you've detected only one memory controller, then work with
only one and do not kill the machine:

diff --git a/drivers/edac/igen6_edac.c b/drivers/edac/igen6_edac.c
index 1930dc00c791..23e26ba2d49b 100644
--- a/drivers/edac/igen6_edac.c
+++ b/drivers/edac/igen6_edac.c
@@ -1350,9 +1350,11 @@ static int igen6_register_mcis(struct pci_dev *pdev, u64 mchbar)
 		return -ENODEV;
 	}
 
-	if (lmc < res_cfg->num_imc)
+	if (lmc < res_cfg->num_imc) {
 		igen6_printk(KERN_WARNING, "Expected %d mcs, but only %d detected.",
 			     res_cfg->num_imc, lmc);
+		res_cfg->num_imc = lmc;
+	}
 
 	return 0;
 
---

but then that cfg struct is const :-\

drivers/edac/igen6_edac.c: In function ‘igen6_register_mcis’:
drivers/edac/igen6_edac.c:1356:34: error: assignment of member ‘num_imc’ in read-only object
 1356 |                 res_cfg->num_imc = lmc;
      |                                  ^


Unless it is some gunky crap this coreboot does - then we will have to have
a longer talk.

:-P

Thx.


-- 
Regards/Gruss,
    Boris.

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