forked from luck/tmp_suning_uos_patched
selftests/x86/test_vsyscall: Improve the process_vm_readv() test
The existing code accepted process_vm_readv() success or failure as long as it didn't return garbage. This is too weak: if the vsyscall page is readable, then process_vm_readv() should succeed and, if the page is not readable, then it should fail. Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: x86@kernel.org Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Jann Horn <jannh@google.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -462,6 +462,17 @@ static int test_vsys_x(void)
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return 0;
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}
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/*
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* Debuggers expect ptrace() to be able to peek at the vsyscall page.
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* Use process_vm_readv() as a proxy for ptrace() to test this. We
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* want it to work in the vsyscall=emulate case and to fail in the
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* vsyscall=xonly case.
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*
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* It's worth noting that this ABI is a bit nutty. write(2) can't
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* read from the vsyscall page on any kernel version or mode. The
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* fact that ptrace() ever worked was a nice courtesy of old kernels,
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* but the code to support it is fairly gross.
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*/
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static int test_process_vm_readv(void)
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{
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#ifdef __x86_64__
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@ -477,8 +488,12 @@ static int test_process_vm_readv(void)
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remote.iov_len = 4096;
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ret = process_vm_readv(getpid(), &local, 1, &remote, 1, 0);
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if (ret != 4096) {
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printf("[OK]\tprocess_vm_readv() failed (ret = %d, errno = %d)\n", ret, errno);
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return 0;
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/*
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* We expect process_vm_readv() to work if and only if the
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* vsyscall page is readable.
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*/
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printf("[%s]\tprocess_vm_readv() failed (ret = %d, errno = %d)\n", vsyscall_map_r ? "FAIL" : "OK", ret, errno);
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return vsyscall_map_r ? 1 : 0;
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}
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if (vsyscall_map_r) {
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@ -488,6 +503,9 @@ static int test_process_vm_readv(void)
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printf("[FAIL]\tIt worked but returned incorrect data\n");
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return 1;
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}
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} else {
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printf("[FAIL]\tprocess_rm_readv() succeeded, but it should have failed in this configuration\n");
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return 1;
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}
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#endif
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