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| author | Andrew Bresticker <abrestic@rivosinc.com> | 2022-09-15 22:37:02 +0300 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2022-09-22 19:44:59 +0300 |
| commit | 9e2e6042a7ec6504fe8e366717afa2f40cf16488 (patch) | |
| tree | 753bd494df1918d2330e0ca0b5739bdfb2b2b53a /arch/riscv/kernel | |
| parent | 7ab72c597356be1e7f0f3d856e54ce78527f43c8 (diff) | |
| download | linux-9e2e6042a7ec6504fe8e366717afa2f40cf16488.tar.xz | |
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 <atishp@rivosinc.com>
Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220915193702.2201018-3-abrestic@rivosinc.com/
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'arch/riscv/kernel')
| -rw-r--r-- | arch/riscv/kernel/sys_riscv.c | 3 |
1 files changed, 0 insertions, 3 deletions
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)); } |