linux-kernel - [PATCH 2/2] riscv: misaligned: fix sleeping function called during misaligned access handling

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Message-Id: <20250411073850.3699180-3-nylon.chen@sifive.com>
Date: Fri, 11 Apr 2025 15:38:50 +0800
From: Nylon Chen <nylon.chen@...ive.com>
To: linux-kernel@...r.kernel.org
Cc: linux-riscv@...ts.infradead.org,
	paul.walmsley@...ive.com,
	palmer@...belt.com,
	aou@...s.berkeley.edu,
	alex@...ti.fr,
	charlie@...osinc.com,
	jesse@...osinc.com,
	evan@...osinc.com,
	nylon.chen@...ive.com,
	cleger@...osinc.com,
	zhangchunyan@...as.ac.cn,
	samuel.holland@...ive.com,
	zong.li@...ive.com
Subject: [PATCH 2/2] riscv: misaligned: fix sleeping function called during misaligned access handling

Use copy_from_user_nofault() and copy_to_user_nofault() instead of
copy_from/to_user functions in the misaligned access trap handlers.

The following bug report was found when executing misaligned memory
accesses:

BUG: sleeping function called from invalid context at ./include/linux/uaccess.h:162
in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 115, name: two
preempt_count: 0, expected: 0
CPU: 0 UID: 0 PID: 115 Comm: two Not tainted 6.14.0-rc5 #24
Hardware name: riscv-virtio,qemu (DT)
Call Trace:
 [<ffffffff800160ea>] dump_backtrace+0x1c/0x24
 [<ffffffff80002304>] show_stack+0x28/0x34
 [<ffffffff80010fae>] dump_stack_lvl+0x4a/0x68
 [<ffffffff80010fe0>] dump_stack+0x14/0x1c
 [<ffffffff8004e44e>] __might_resched+0xfa/0x104
 [<ffffffff8004e496>] __might_sleep+0x3e/0x62
 [<ffffffff801963c4>] __might_fault+0x1c/0x24
 [<ffffffff80425352>] _copy_from_user+0x28/0xaa
 [<ffffffff8000296c>] handle_misaligned_store+0x204/0x254
 [<ffffffff809eae82>] do_trap_store_misaligned+0x24/0xee
 [<ffffffff809f4f1a>] handle_exception+0x146/0x152

Fixes: b686ecdeacf6 ("riscv: misaligned: Restrict user access to kernel memory")
Fixes: 441381506ba7 ("riscv: misaligned: remove CONFIG_RISCV_M_MODE specific code")

Signed-off-by: Zong Li <zong.li@...ive.com>
Signed-off-by: Nylon Chen <nylon.chen@...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 d7275dfb6b7e..563f73f88fa8 100644
--- a/arch/riscv/kernel/traps_misaligned.c
+++ b/arch/riscv/kernel/traps_misaligned.c
@@ -455,7 +455,7 @@ static int handle_scalar_misaligned_load(struct pt_regs *regs)
 
 	val.data_u64 = 0;
 	if (user_mode(regs)) {
-		if (copy_from_user(&val, (u8 __user *)addr, len))
+		if (copy_from_user_nofault(&val, (u8 __user *)addr, len))
 			return -1;
 	} else {
 		memcpy(&val, (u8 *)addr, len);
@@ -556,7 +556,7 @@ static int handle_scalar_misaligned_store(struct pt_regs *regs)
 		return -EOPNOTSUPP;
 
 	if (user_mode(regs)) {
-		if (copy_to_user((u8 __user *)addr, &val, len))
+		if (copy_to_user_nofault((u8 __user *)addr, &val, len))
 			return -1;
 	} else {
 		memcpy((u8 *)addr, &val, len);
-- 
2.34.1