[PATCH 5.0 077/117] riscv: Fix syscall_get_arguments() and syscall_set_arguments()

Greg Kroah-Hartman
2019-04-15T19:12:58Z

From: Dmitry V. Levin <ldv@altlinux.org>

commit 10a16997db3d99fc02c026cf2c6e6c670acafab0 upstream.

RISC-V syscall arguments are located in orig_a0,a1..a5 fields
of struct pt_regs.

Due to an off-by-one bug and a bug in pointer arithmetic
syscall_get_arguments() was reading s3..s7 fields instead of a1..a5.
Likewise, syscall_set_arguments() was writing s3..s7 fields
instead of a1..a5.

Link: http://lkml.kernel.org/r/20190329171221.GA32456@altlinux.org

Fixes: e2c0cdfba7f69 ("RISC-V: User-facing API")
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: linux-riscv@lists.infradead.org
Cc: stable@vger.kernel.org # v4.15+
Acked-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/riscv/include/asm/syscall.h | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

--- a/arch/riscv/include/asm/syscall.h
+++ b/arch/riscv/include/asm/syscall.h
@@ -79,10 +79,11 @@ static inline void syscall_get_arguments
if (i == 0) {
args[0] = regs->orig_a0;
args++;
- i++;
n--;
+ } else {
+ i--;
}
- memcpy(args, &regs->a1 + i * sizeof(regs->a1), n * sizeof(args[0]));
+ memcpy(args, &regs->a1 + i, n * sizeof(args[0]));
}

static inline void syscall_set_arguments(struct task_struct *task,
@@ -94,10 +95,11 @@ static inline void syscall_set_arguments
if (i == 0) {
regs->orig_a0 = args[0];
args++;
- i++;
n--;
- }
- memcpy(&regs->a1 + i * sizeof(regs->a1), args, n * sizeof(regs->a0));
+ } else {
+ i--;
+ }
+ memcpy(&regs->a1 + i, args, n * sizeof(regs->a1));
}

static inline int syscall_get_arch(void)