From mboxrd@z Thu Jan 1 00:00:00 1970 From: alex.shi@linaro.org (Alex Shi) Date: Fri, 9 Mar 2018 17:06:53 +0800 Subject: [PATCH 10/39] arm64: futex: Mask __user pointers prior to dereference In-Reply-To: <20180309090722.26279-1-alex.shi@linaro.org> References: <20180309090722.26279-1-alex.shi@linaro.org> Message-ID: <20180309090722.26279-11-alex.shi@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Will Deacon commit 91b2d3442f6a upstream. The arm64 futex code has some explicit dereferencing of user pointers where performing atomic operations in response to a futex command. This patch uses masking to limit any speculative futex operations to within the user address space. Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Alex Shi --- arch/arm64/include/asm/futex.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h index 5f3ab8c1db55..27eebc6f6976 100644 --- a/arch/arm64/include/asm/futex.h +++ b/arch/arm64/include/asm/futex.h @@ -53,13 +53,14 @@ : "memory") static inline int -futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr) +futex_atomic_op_inuser (int encoded_op, u32 __user *_uaddr) { int op = (encoded_op >> 28) & 7; int cmp = (encoded_op >> 24) & 15; int oparg = (encoded_op << 8) >> 20; int cmparg = (encoded_op << 20) >> 20; int oldval = 0, ret, tmp; + u32 __user *uaddr = __uaccess_mask_ptr(_uaddr); if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) oparg = 1 << oparg; @@ -111,15 +112,17 @@ futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr) } static inline int -futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, +futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr, u32 oldval, u32 newval) { int ret = 0; u32 val, tmp; + u32 __user *uaddr; - if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) + if (!access_ok(VERIFY_WRITE, _uaddr, sizeof(u32))) return -EFAULT; + uaddr = __uaccess_mask_ptr(_uaddr); asm volatile("// futex_atomic_cmpxchg_inatomic\n" ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN) " prfm pstl1strm, %2\n" -- 2.16.2.440.gc6284da