From 9e2e6042a7ec6504fe8e366717afa2f40cf16488 Mon Sep 17 00:00:00 2001 From: Andrew Bresticker Date: Thu, 15 Sep 2022 15:37:02 -0400 Subject: riscv: Allow PROT_WRITE-only mmap() Commit 2139619bcad7 ("riscv: mmap with PROT_WRITE but no PROT_READ is invalid") made mmap() return EINVAL if PROT_WRITE was set wihtout PROT_READ with the justification that a write-only PTE is considered a reserved PTE permission bit pattern in the privileged spec. This check is unnecessary since we let VM_WRITE imply VM_READ on RISC-V, and it is inconsistent with other architectures that don't support write-only PTEs, creating a potential software portability issue. Just remove the check altogether and let PROT_WRITE imply PROT_READ as is the case on other architectures. Note that this also allows PROT_WRITE|PROT_EXEC mappings which were disallowed prior to the aforementioned commit; PROT_READ is implied in such mappings as well. Fixes: 2139619bcad7 ("riscv: mmap with PROT_WRITE but no PROT_READ is invalid") Reviewed-by: Atish Patra Signed-off-by: Andrew Bresticker Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20220915193702.2201018-3-abrestic@rivosinc.com/ Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/sys_riscv.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'arch/riscv/kernel/sys_riscv.c') diff --git a/arch/riscv/kernel/sys_riscv.c b/arch/riscv/kernel/sys_riscv.c index 571556bb9261..5d3f2fbeb33c 100644 --- a/arch/riscv/kernel/sys_riscv.c +++ b/arch/riscv/kernel/sys_riscv.c @@ -18,9 +18,6 @@ static long riscv_sys_mmap(unsigned long addr, unsigned long len, if (unlikely(offset & (~PAGE_MASK >> page_shift_offset))) 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)); } -- cgit