[PATCH AUTOSEL 4.19 05/14] riscv: mmap with PROT_WRITE but no PROT_READ is invalid

[Sasha Levin]

From: Celeste Liu <coelacanthus at outlook.com>

[ 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 at outlook.com>
Co-developed-by: dram <dramforever at live.com>
Signed-off-by: dram <dramforever at live.com>
Co-developed-by: Ruizhe Pan <c141028 at gmail.com>
Signed-off-by: Ruizhe Pan <c141028 at gmail.com>
Signed-off-by: Celeste Liu <coelacanthus at outlook.com>
Link: https://lore.kernel.org/r/PH7PR14MB559464DBDD310E755F5B21E8CEDC9@PH7PR14MB5594.namprd14.prod.outlook.com
Signed-off-by: Palmer Dabbelt <palmer at rivosinc.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 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 db44da32701f..516aaa19daf2 100644
--- a/arch/riscv/kernel/sys_riscv.c
+++ b/arch/riscv/kernel/sys_riscv.c
@@ -26,9 +26,8 @@ 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