linux-kernel - [PATCH 06/13] powerpc/pseries/nvram: Unpoison buffer populated by rtas

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Message-Id: <20231214055539.9420-7-nicholas@linux.ibm.com>
Date:   Thu, 14 Dec 2023 05:55:32 +0000
From:   Nicholas Miehlbradt <nicholas@...ux.ibm.com>
To:     glider@...gle.com, elver@...gle.com, dvyukov@...gle.com,
        akpm@...ux-foundation.org, mpe@...erman.id.au, npiggin@...il.com,
        christophe.leroy@...roup.eu
Cc:     linux-mm@...ck.org, kasan-dev@...glegroups.com, iii@...ux.ibm.com,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Nicholas Miehlbradt <nicholas@...ux.ibm.com>
Subject: [PATCH 06/13] powerpc/pseries/nvram: Unpoison buffer populated by rtas_call

rtas_call provides a buffer where the return data should be placed. Rtas
initializes the buffer which is not visible to KMSAN so unpoison it
manually.

Signed-off-by: Nicholas Miehlbradt <nicholas@...ux.ibm.com>
---
 arch/powerpc/platforms/pseries/nvram.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/nvram.c b/arch/powerpc/platforms/pseries/nvram.c
index 8130c37962c0..21a27d459347 100644
--- a/arch/powerpc/platforms/pseries/nvram.c
+++ b/arch/powerpc/platforms/pseries/nvram.c
@@ -14,6 +14,7 @@
 #include <linux/ctype.h>
 #include <linux/uaccess.h>
 #include <linux/of.h>
+#include <linux/kmsan-checks.h>
 #include <asm/nvram.h>
 #include <asm/rtas.h>
 #include <asm/machdep.h>
@@ -41,6 +42,7 @@ static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
 	int done;
 	unsigned long flags;
 	char *p = buf;
+	size_t l;
 
 
 	if (nvram_size == 0 || nvram_fetch == RTAS_UNKNOWN_SERVICE)
@@ -53,6 +55,7 @@ static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
 	if (i + count > nvram_size)
 		count = nvram_size - i;
 
+	l = count;
 	spin_lock_irqsave(&nvram_lock, flags);
 
 	for (; count != 0; count -= len) {
@@ -73,6 +76,7 @@ static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
 	}
 
 	spin_unlock_irqrestore(&nvram_lock, flags);
+	kmsan_unpoison_memory(buf, l);
 	
 	*index = i;
 	return p - buf;
-- 
2.40.1