linux-kernel - [PATCH 4.9 27/33] EDAC: Fix calculation of returned address and next offset in edac_align

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Message-Id: <20220221084909.645481616@linuxfoundation.org>
Date:   Mon, 21 Feb 2022 09:49:20 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eliav Farber <farbere@...zon.com>,
        Borislav Petkov <bp@...e.de>
Subject: [PATCH 4.9 27/33] EDAC: Fix calculation of returned address and next offset in edac_align_ptr()

From: Eliav Farber <farbere@...zon.com>

commit f8efca92ae509c25e0a4bd5d0a86decea4f0c41e upstream.

Do alignment logic properly and use the "ptr" local variable for
calculating the remainder of the alignment.

This became an issue because struct edac_mc_layer has a size that is not
zero modulo eight, and the next offset that was prepared for the private
data was unaligned, causing an alignment exception.

The patch in Fixes: which broke this actually wanted to "what we
actually care about is the alignment of the actual pointer that's about
to be returned." But it didn't check that alignment.

Use the correct variable "ptr" for that.

  [ bp: Massage commit message. ]

Fixes: 8447c4d15e35 ("edac: Do alignment logic properly in edac_align_ptr()")
Signed-off-by: Eliav Farber <farbere@...zon.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/20220113100622.12783-2-farbere@amazon.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/edac/edac_mc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -199,7 +199,7 @@ void *edac_align_ptr(void **p, unsigned
 	else
 		return (char *)ptr;

-	r = (unsigned long)p % align;
+	r = (unsigned long)ptr % align;

 	if (r == 0)
 		return (char *)ptr;