linux-kernel - [PATCH -fixes] riscv: Fix wrong usage of lm_alias() when splitting a huge linear mapping

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Message-Id: <20231211141929.74027-1-alexghiti@rivosinc.com>
Date:   Mon, 11 Dec 2023 15:19:29 +0100
From:   Alexandre Ghiti <alexghiti@...osinc.com>
To:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Alexandre Ghiti <alexghiti@...osinc.com>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     syzbot+afb726d49f84c8d95ee1@...kaller.appspotmail.com
Subject: [PATCH -fixes] riscv: Fix wrong usage of lm_alias() when splitting a huge linear mapping

lm_alias() can only be used on kernel mappings since it explicitly uses
__pa_symbol(), so simply fix this by checking where the address belongs
to before.

Fixes: 311cd2f6e253 ("riscv: Fix set_memory_XX() and set_direct_map_XX() by splitting huge linear mappings")
Reported-by: syzbot+afb726d49f84c8d95ee1@...kaller.appspotmail.com
Closes: https://lore.kernel.org/linux-riscv/000000000000620dd0060c02c5e1@google.com/
Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
---
 arch/riscv/mm/pageattr.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
index fc5fc4f785c4..f5f8aa1d38d6 100644
--- a/arch/riscv/mm/pageattr.c
+++ b/arch/riscv/mm/pageattr.c
@@ -304,9 +304,16 @@ static int __set_memory(unsigned long addr, int numpages, pgprot_t set_mask,
 			if (ret)
 				goto unlock;
 		}
-	} else if (is_kernel_mapping(start) || is_linear_mapping(start)) {
-		lm_start = (unsigned long)lm_alias(start);
-		lm_end = (unsigned long)lm_alias(end);
+	} else {
+		if (is_kernel_mapping(start)) {
+			lm_start = (unsigned long)lm_alias(start);
+			lm_end = (unsigned long)lm_alias(end);
+		} else if (is_linear_mapping(start)) {
+			lm_start = start;
+			lm_end = end;
+		} else {
+			goto unlock;
+		}
 
 		ret = split_linear_mapping(lm_start, lm_end);
 		if (ret)
-- 
2.39.2