linux-kernel - [PATCH] riscv: misaligned: Restrict user access to kernel memory

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Message-ID: <20240815005714.1163136-1-samuel.holland@sifive.com>
Date: Wed, 14 Aug 2024 17:57:03 -0700
From: Samuel Holland <samuel.holland@...ive.com>
To: Palmer Dabbelt <palmer@...belt.com>
Cc: Samuel Holland <samuel.holland@...ive.com>,
	stable@...r.kernel.org,
	Albert Ou <aou@...s.berkeley.edu>,
	Ben Dooks <ben.dooks@...ethink.co.uk>,
	Björn Töpel <bjorn@...osinc.com>,
	Charlie Jenkins <charlie@...osinc.com>,
	Clément Léger <cleger@...osinc.com>,
	Conor Dooley <conor.dooley@...rochip.com>,
	Evan Green <evan@...osinc.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org
Subject: [PATCH] riscv: misaligned: Restrict user access to kernel memory

raw_copy_{to,from}_user() do not call access_ok(), so this code allowed
userspace to access any virtual memory address.

Cc: stable@...r.kernel.org
Fixes: 7c83232161f6 ("riscv: add support for misaligned trap handling in S-mode")
Fixes: 441381506ba7 ("riscv: misaligned: remove CONFIG_RISCV_M_MODE specific code")
Signed-off-by: Samuel Holland <samuel.holland@...ive.com>
---

 arch/riscv/kernel/traps_misaligned.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c
index b62d5a2f4541..1a76f99ff185 100644
--- a/arch/riscv/kernel/traps_misaligned.c
+++ b/arch/riscv/kernel/traps_misaligned.c
@@ -417,7 +417,7 @@ int handle_misaligned_load(struct pt_regs *regs)
 
 	val.data_u64 = 0;
 	if (user_mode(regs)) {
-		if (raw_copy_from_user(&val, (u8 __user *)addr, len))
+		if (copy_from_user(&val, (u8 __user *)addr, len))
 			return -1;
 	} else {
 		memcpy(&val, (u8 *)addr, len);
@@ -515,7 +515,7 @@ int handle_misaligned_store(struct pt_regs *regs)
 		return -EOPNOTSUPP;
 
 	if (user_mode(regs)) {
-		if (raw_copy_to_user((u8 __user *)addr, &val, len))
+		if (copy_to_user((u8 __user *)addr, &val, len))
 			return -1;
 	} else {
 		memcpy((u8 *)addr, &val, len);
-- 
2.45.1