[PATCH 5.4 374/389] riscv: mmap with PROT_WRITE but no PROT_READ is invalid

[Greg Kroah-Hartman]

From: Celeste Liu <coelacanthus@xxxxxxxxxxx>

[ Upstream commit 2139619bcad7ac44cc8f6f749089120594056613 ]

As mentioned in Table 4.5 in RISC-V spec Volume 2 Section 4.3, write
but not read is "Reserved for future use.". For now, they are not valid.
In the current code, -wx is marked as invalid, but -w- is not marked
as invalid.
This patch refines that judgment.

Reported-by: xctan <xc-tan@xxxxxxxxxxx>
Co-developed-by: dram <dramforever@xxxxxxxx>
Signed-off-by: dram <dramforever@xxxxxxxx>
Co-developed-by: Ruizhe Pan <c141028@xxxxxxxxx>
Signed-off-by: Ruizhe Pan <c141028@xxxxxxxxx>
Signed-off-by: Celeste Liu <coelacanthus@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/PH7PR14MB559464DBDD310E755F5B21E8CEDC9@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 arch/riscv/kernel/sys_riscv.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/sys_riscv.c b/arch/riscv/kernel/sys_riscv.c
index 12f8a7fce78b..8a7880b9c433 100644
--- a/arch/riscv/kernel/sys_riscv.c
+++ b/arch/riscv/kernel/sys_riscv.c
@@ -18,9 +18,8 @@ static long riscv_sys_mmap(unsigned long addr, unsigned long len,
 	if (unlikely(offset & (~PAGE_MASK >> page_shift_offset)))
 		return -EINVAL;
 
-	if ((prot & PROT_WRITE) && (prot & PROT_EXEC))
-		if (unlikely(!(prot & PROT_READ)))
-			return -EINVAL;
+	if (unlikely((prot & PROT_WRITE) && !(prot & PROT_READ)))
+		return -EINVAL;
 
 	return ksys_mmap_pgoff(addr, len, prot, flags, fd,
 			       offset >> (PAGE_SHIFT - page_shift_offset));
-- 
2.35.1