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[89.3.178.76]) by smtp.gmail.com with ESMTPSA id 14sm1629981wmv.36.2018.12.06.07.02.14 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 06 Dec 2018 07:02:15 -0800 (PST) From: David Abdurachmanov To: palmer@sifive.com, aou@eecs.berkeley.edu, keescook@chromium.org, luto@amacapital.net, wad@chromium.org, green.hu@gmail.com, deanbo422@gmail.com, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Cc: David Abdurachmanov Subject: [PATCH 2/2] riscv: fix syscall_{get,set}_arguments Date: Thu, 6 Dec 2018 16:01:56 +0100 Message-Id: <20181206150156.28210-3-david.abdurachmanov@gmail.com> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181206150156.28210-1-david.abdurachmanov@gmail.com> References: <20181206150156.28210-1-david.abdurachmanov@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Testing with libseccomp master branch revealed that testcases with filters on syscall arguments were failing due to wrong values. Seccomp uses syscall_get_argumentsi() to copy syscall arguments, and there is a bug in pointer arithmetics in memcpy() call. Two alternative implementation were tested: the one in this patch and another one based on while-break loop. Both delivered the same results. This implementation is also used in arm, arm64 and nds32 arches. Signed-off-by: David Abdurachmanov --- arch/riscv/include/asm/syscall.h | 42 ++++++++++++++++++++++++-------- 1 file changed, 32 insertions(+), 10 deletions(-) diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h index bba3da6ef157..26ceb434a433 100644 --- a/arch/riscv/include/asm/syscall.h +++ b/arch/riscv/include/asm/syscall.h @@ -70,19 +70,32 @@ static inline void syscall_set_return_value(struct task_struct *task, regs->a0 = (long) error ?: val; } +#define SYSCALL_MAX_ARGS 6 + static inline void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs, unsigned int i, unsigned int n, unsigned long *args) { - BUG_ON(i + n > 6); + if (n == 0) + return; + + if (i + n > SYSCALL_MAX_ARGS) { + unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i; + unsigned int n_bad = n + i - SYSCALL_MAX_ARGS; + pr_warning("%s called with max args %d, handling only %d\n", + __func__, i + n, SYSCALL_MAX_ARGS); + memset(args_bad, 0, n_bad * sizeof(args[0])); + } + if (i == 0) { args[0] = regs->orig_a0; args++; i++; n--; } - memcpy(args, ®s->a1 + i * sizeof(regs->a1), n * sizeof(args[0])); + + memcpy(args, ®s->a0 + i, n * sizeof(args[0])); } static inline void syscall_set_arguments(struct task_struct *task, @@ -90,14 +103,23 @@ static inline void syscall_set_arguments(struct task_struct *task, unsigned int i, unsigned int n, const unsigned long *args) { - BUG_ON(i + n > 6); - if (i == 0) { - regs->orig_a0 = args[0]; - args++; - i++; - n--; - } - memcpy(®s->a1 + i * sizeof(regs->a1), args, n * sizeof(regs->a0)); + if (n == 0) + return; + + if (i + n > SYSCALL_MAX_ARGS) { + pr_warning("%s called with max args %d, handling only %d\n", + __func__, i + n, SYSCALL_MAX_ARGS); + n = SYSCALL_MAX_ARGS - i; + } + + if (i == 0) { + regs->orig_a0 = args[0]; + args++; + i++; + n--; + } + + memcpy(®s->a0 + i, args, n * sizeof(args[0])); } static inline int syscall_get_arch(void) -- 2.19.2