From e4e8e5d28d5e1dac24f775452d4cc6f49f5c069e Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Sat, 12 Sep 2020 04:08:15 -0700
Subject: [PATCH] selftests/seccomp: Avoid redundant register flushes
When none of the registers have changed, don't flush them back. This can
happen if the architecture uses a non-register way to change the syscall
(e.g. arm64) , and a return value hasn't been written.
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/lkml/20200912110820.597135-11-keescook@chromium.org
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
---
tools/testing/selftests/seccomp/seccomp_bpf.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index 00056e067846a1..638cea8cb23dbc 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -1859,11 +1859,12 @@ int get_syscall(struct __test_metadata *_metadata, pid_t tracee)
void change_syscall(struct __test_metadata *_metadata,
pid_t tracee, int syscall, int result)
{
- ARCH_REGS regs;
+ ARCH_REGS orig, regs;
EXPECT_EQ(0, ARCH_GETREGS(regs)) {
return;
}
+ orig = regs;
SYSCALL_NUM_SET(regs, syscall);
@@ -1876,7 +1877,8 @@ void change_syscall(struct __test_metadata *_metadata,
#endif
/* Flush any register changes made. */
- EXPECT_EQ(0, ARCH_SETREGS(regs));
+ if (memcmp(&orig, ®s, sizeof(orig)) != 0)
+ EXPECT_EQ(0, ARCH_SETREGS(regs));
}
void tracer_seccomp(struct __test_metadata *_metadata, pid_t tracee,
--
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