linux-kernel - [PATCH v2 3/3] riscv: Fix crash when flushing executable ioremap regions

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Message-Id: <8a555b0b0934f0ba134de92f6cf9db8b1744316c.1581767384.git.jan.kiszka@web.de>
Date:   Sat, 15 Feb 2020 12:49:44 +0100
From:   Jan Kiszka <jan.kiszka@....de>
To:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        linux-riscv@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/3] riscv: Fix crash when flushing executable ioremap regions

From: Jan Kiszka <jan.kiszka@...mens.com>

Those are not backed by page structs, and pte_page is returning an
invalid pointer.

Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
---
 arch/riscv/mm/cacheflush.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c
index 8930ab7278e6..9ee2c1a387cc 100644
--- a/arch/riscv/mm/cacheflush.c
+++ b/arch/riscv/mm/cacheflush.c
@@ -84,7 +84,8 @@ void flush_icache_pte(pte_t pte)
 {
 	struct page *page = pte_page(pte);

-	if (!test_and_set_bit(PG_dcache_clean, &page->flags))
+	if (!pfn_valid(pte_pfn(pte)) ||
+	    !test_and_set_bit(PG_dcache_clean, &page->flags))
 		flush_icache_all();
 }
 #endif /* CONFIG_MMU */
--
2.16.4