On Thu, Aug 27, 2020 at 02:02:27PM +0000, Shiju Jose wrote: > I tested with your changes and it fixes the issue. I will send v2.
Btw, I don't know how it managed to work on your machine because even with this patch, it isn't all fixed because num_dimms needs to be cleared too, see here: --- From: Borislav Petkov <[email protected]> Date: Fri, 11 Sep 2020 12:55:55 +0200 Subject: [PATCH] EDAC/ghes: Clear scanned data on unload Commit b972fdba8665 ("EDAC/ghes: Fix NULL pointer dereference in ghes_edac_register()") didn't clear all the information from the scanned system and, more specifically, left ghes_hw.num_dimms to its previous value. On a second load (CONFIG_DEBUG_TEST_DRIVER_REMOVE=y), the driver would use the leftover num_dimms value which is not 0 and thus the 0 check in enumerate_dimms() will get bypassed and it would go directly to the pointer deref: d = &hw->dimms[hw->num_dimms]; which is, of course, NULL: #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] PREEMPT SMP CPU: 7 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc4+ #7 Hardware name: GIGABYTE MZ01-CE1-00/MZ01-CE1-00, BIOS F02 08/29/2018 RIP: 0010:enumerate_dimms.cold+0x7b/0x375 Reset the whole ghes_hw on driver unregister so that no stale values are used on a second system scan. Fixes: b972fdba8665 ("EDAC/ghes: Fix NULL pointer dereference in ghes_edac_register()") Cc: Shiju Jose <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> --- drivers/edac/ghes_edac.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c index a6b9c0b2a15c..eb6034a6fbbb 100644 --- a/drivers/edac/ghes_edac.c +++ b/drivers/edac/ghes_edac.c @@ -632,6 +632,7 @@ void ghes_edac_unregister(struct ghes *ghes) mutex_lock(&ghes_reg_mutex); system_scanned = false; + memset(&ghes_hw, 0, sizeof(struct ghes_hw_desc)); if (!refcount_dec_and_test(&ghes_refcount)) goto unlock; -- 2.21.0 -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
