[PATCH 4.1 39/78] MIPS: Fix seccomp syscall argument for MIPS64

Greg Kroah-Hartman
2015-09-11T22:58:07Z

From: Markos Chandras <markos.chandras@imgtec.com>

commit 9f161439e4104b641a7bfb9b89581d801159fec8 upstream.

Commit 4c21b8fd8f14 ("MIPS: seccomp: Handle indirect system calls (o32)")
fixed indirect system calls on O32 but it also introduced a bug for MIPS64
where it erroneously modified the v0 (syscall) register with the assumption
that the sycall offset hasn't been taken into consideration. This breaks
seccomp on MIPS64 n64 and n32 ABIs. We fix this by replacing the addition
with a move instruction.

Fixes: 4c21b8fd8f14 ("MIPS: seccomp: Handle indirect system calls (o32)")
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10951/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/mips/kernel/scall64-64.S | 2 +-
arch/mips/kernel/scall64-n32.S | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

--- a/arch/mips/kernel/scall64-64.S
+++ b/arch/mips/kernel/scall64-64.S
@@ -80,7 +80,7 @@ syscall_trace_entry:
SAVE_STATIC
move s0, t2
move a0, sp
- daddiu a1, v0, __NR_64_Linux
+ move a1, v0
jal syscall_trace_enter

bltz v0, 2f # seccomp failed? Skip syscall
--- a/arch/mips/kernel/scall64-n32.S
+++ b/arch/mips/kernel/scall64-n32.S
@@ -72,7 +72,7 @@ n32_syscall_trace_entry:
SAVE_STATIC
move s0, t2
move a0, sp
- daddiu a1, v0, __NR_N32_Linux
+ move a1, v0
jal syscall_trace_enter

bltz v0, 2f # seccomp failed? Skip syscall