[PATCH AUTOSEL 5.19 20/48] riscv: mmap with PROT_WRITE but no PROT_READ is invalid

From: Sasha Levin
Date: Sun Aug 14 2022 - 12:24:06 EST


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 9c0194f176fc..571556bb9261 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