linux-kernel - [PATCH mm] fix for "kasan, vmalloc: only tag normal vmalloc allocations"

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Message-Id: <de4587d6a719232e83c760113e46ed2d4d8da61e.1646757322.git.andreyknvl@google.com>
Date:   Tue,  8 Mar 2022 17:54:17 +0100
From:   andrey.konovalov@...ux.dev
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Andrey Konovalov <andreyknvl@...il.com>,
        Marco Elver <elver@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        kasan-dev@...glegroups.com, Vasily Gorbik <gor@...ux.ibm.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH mm] fix for "kasan, vmalloc: only tag normal vmalloc allocations"

From: Andrey Konovalov <andreyknvl@...gle.com>

"kasan, vmalloc: only tag normal vmalloc allocations" unintentionally
disabled poisoning of executable memory for the Generic mode. Fix it.

Reported-by: Vasily Gorbik <gor@...ux.ibm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 mm/kasan/shadow.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
index 7272e248db87..a4f07de21771 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -489,10 +489,11 @@ void *__kasan_unpoison_vmalloc(const void *start, unsigned long size,
 		return (void *)start;
 
 	/*
-	 * Don't tag executable memory.
+	 * Don't tag executable memory with the tag-based mode.
 	 * The kernel doesn't tolerate having the PC register tagged.
 	 */
-	if (!(flags & KASAN_VMALLOC_PROT_NORMAL))
+	if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) &&
+	    !(flags & KASAN_VMALLOC_PROT_NORMAL))
 		return (void *)start;
 
 	start = set_tag(start, kasan_random_tag());
-- 
2.25.1