From 79b4a9cf0e2ea8203ce777c8d5cfa86c71eae86e Mon Sep 17 00:00:00 2001 From: Aurelien Jarno Date: Tue, 9 Apr 2019 16:53:55 +0200 Subject: [PATCH] MIPS: scall64-o32: Fix indirect syscall number load MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit 4c21b8fd8f14 (MIPS: seccomp: Handle indirect system calls (o32)) added indirect syscall detection for O32 processes running on MIPS64, but it did not work correctly for big endian kernel/processes. The reason is that the syscall number is loaded from ARG1 using the lw instruction while this is a 64-bit value, so zero is loaded instead of the syscall number. Fix the code by using the ld instruction instead. When running a 32-bit processes on a 64 bit CPU, the values are properly sign-extended, so it ensures the value passed to syscall_trace_enter is correct. Recent systemd versions with seccomp enabled whitelist the getpid syscall for their internal processes (e.g. systemd-journald), but call it through syscall(SYS_getpid). This fix therefore allows O32 big endian systems with a 64-bit kernel to run recent systemd versions. Signed-off-by: Aurelien Jarno Cc: # v3.15+ Reviewed-by: Philippe Mathieu-Daudé Signed-off-by: Paul Burton Cc: Ralf Baechle Cc: James Hogan Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- arch/mips/kernel/scall64-o32.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S index f158c5894a9a..feb2653490df 100644 --- a/arch/mips/kernel/scall64-o32.S +++ b/arch/mips/kernel/scall64-o32.S @@ -125,7 +125,7 @@ trace_a_syscall: subu t1, v0, __NR_O32_Linux move a1, v0 bnez t1, 1f /* __NR_syscall at offset 0 */ - lw a1, PT_R4(sp) /* Arg1 for __NR_syscall case */ + ld a1, PT_R4(sp) /* Arg1 for __NR_syscall case */ .set pop 1: jal syscall_trace_enter