From: Andrew Bresticker <abrestic@rivosinc.com> To: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com>, Celeste Liu <coelacanthus@outlook.com>, dram <dramforever@live.com>, Ruizhe Pan <c141028@gmail.com>, Conor.Dooley@microchip.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Andrew Bresticker <abrestic@rivosinc.com>, stable@vger.kernel.org, Atish Patra <atishp@rivosinc.com> Subject: [PATCH v4 2/2] riscv: Allow PROT_WRITE-only mmap() Date: Thu, 15 Sep 2022 15:37:02 -0400 [thread overview] Message-ID: <20220915193702.2201018-3-abrestic@rivosinc.com> (raw) In-Reply-To: <20220915193702.2201018-1-abrestic@rivosinc.com> 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") Cc: <stable@vger.kernel.org> # v4.19+ Reviewed-by: Atish Patra <atishp@rivosinc.com> Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com> --- v1 -> v2: Update access_error() to account for write-implies-read v2 -> v3: Separate into two commits --- arch/riscv/kernel/sys_riscv.c | 3 --- 1 file changed, 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)); } -- 2.25.1 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Bresticker <abrestic@rivosinc.com> To: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com>, Celeste Liu <coelacanthus@outlook.com>, dram <dramforever@live.com>, Ruizhe Pan <c141028@gmail.com>, Conor.Dooley@microchip.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Andrew Bresticker <abrestic@rivosinc.com>, stable@vger.kernel.org, Atish Patra <atishp@rivosinc.com> Subject: [PATCH v4 2/2] riscv: Allow PROT_WRITE-only mmap() Date: Thu, 15 Sep 2022 15:37:02 -0400 [thread overview] Message-ID: <20220915193702.2201018-3-abrestic@rivosinc.com> (raw) In-Reply-To: <20220915193702.2201018-1-abrestic@rivosinc.com> 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") Cc: <stable@vger.kernel.org> # v4.19+ Reviewed-by: Atish Patra <atishp@rivosinc.com> Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com> --- v1 -> v2: Update access_error() to account for write-implies-read v2 -> v3: Separate into two commits --- arch/riscv/kernel/sys_riscv.c | 3 --- 1 file changed, 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)); } -- 2.25.1
next prev parent reply other threads:[~2022-09-15 19:37 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-09-15 19:37 [PATCH v4 0/2] Make mmap() with PROT_WRITE imply PROT_READ Andrew Bresticker 2022-09-15 19:37 ` Andrew Bresticker 2022-09-15 19:37 ` [PATCH v4 1/2] riscv: Make VM_WRITE imply VM_READ Andrew Bresticker 2022-09-15 19:37 ` Andrew Bresticker 2022-09-15 19:37 ` Andrew Bresticker [this message] 2022-09-15 19:37 ` [PATCH v4 2/2] riscv: Allow PROT_WRITE-only mmap() Andrew Bresticker 2022-10-11 17:04 ` [PATCH v4 0/2] Make mmap() with PROT_WRITE imply PROT_READ Conor Dooley 2022-10-11 17:04 ` Conor Dooley 2022-10-13 21:01 ` Palmer Dabbelt 2022-10-13 21:01 ` Palmer Dabbelt
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