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ebiedermebiederm
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signal/x86: Include the field offsets in the build time checks
Due to an oversight when refactoring siginfo_t si_pkey has been in the wrong position since 4.16-rc1. Add an explicit check of the offset of every user space field in siginfo_t and compat_siginfo_t to make a mistake like this hard to make in the future. I have run this code on 4.15 and 4.16-rc1 with the position of si_pkey fixed and all of the fields show up in the same location. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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‎arch/x86/kernel/signal_compat.c

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Original file line numberDiff line numberDiff line change
@@ -43,6 +43,13 @@ static inline void signal_compat_build_tests(void)
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BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields) != 3 * sizeof(int));
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#define CHECK_CSI_OFFSET(name) BUILD_BUG_ON(_sifields_offset != offsetof(compat_siginfo_t, _sifields.name))
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BUILD_BUG_ON(offsetof(siginfo_t, si_signo) != 0);
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BUILD_BUG_ON(offsetof(siginfo_t, si_errno) != 4);
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BUILD_BUG_ON(offsetof(siginfo_t, si_code) != 8);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_signo) != 0);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_errno) != 4);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_code) != 8);
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/*
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* Ensure that the size of each si_field never changes.
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* If it does, it is a sign that the
@@ -63,36 +70,94 @@ static inline void signal_compat_build_tests(void)
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CHECK_CSI_SIZE (_kill, 2*sizeof(int));
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CHECK_SI_SIZE (_kill, 2*sizeof(int));
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BUILD_BUG_ON(offsetof(siginfo_t, si_pid) != 0x10);
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BUILD_BUG_ON(offsetof(siginfo_t, si_uid) != 0x14);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid) != 0xC);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid) != 0x10);
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CHECK_CSI_OFFSET(_timer);
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CHECK_CSI_SIZE (_timer, 3*sizeof(int));
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CHECK_SI_SIZE (_timer, 6*sizeof(int));
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BUILD_BUG_ON(offsetof(siginfo_t, si_tid) != 0x10);
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BUILD_BUG_ON(offsetof(siginfo_t, si_overrun) != 0x14);
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BUILD_BUG_ON(offsetof(siginfo_t, si_value) != 0x18);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_tid) != 0x0C);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_overrun) != 0x10);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_value) != 0x14);
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CHECK_CSI_OFFSET(_rt);
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CHECK_CSI_SIZE (_rt, 3*sizeof(int));
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CHECK_SI_SIZE (_rt, 4*sizeof(int));
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BUILD_BUG_ON(offsetof(siginfo_t, si_pid) != 0x10);
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BUILD_BUG_ON(offsetof(siginfo_t, si_uid) != 0x14);
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BUILD_BUG_ON(offsetof(siginfo_t, si_value) != 0x18);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid) != 0x0C);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid) != 0x10);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_value) != 0x14);
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CHECK_CSI_OFFSET(_sigchld);
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CHECK_CSI_SIZE (_sigchld, 5*sizeof(int));
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CHECK_SI_SIZE (_sigchld, 8*sizeof(int));
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BUILD_BUG_ON(offsetof(siginfo_t, si_pid) != 0x10);
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BUILD_BUG_ON(offsetof(siginfo_t, si_uid) != 0x14);
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BUILD_BUG_ON(offsetof(siginfo_t, si_status) != 0x18);
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BUILD_BUG_ON(offsetof(siginfo_t, si_utime) != 0x20);
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BUILD_BUG_ON(offsetof(siginfo_t, si_stime) != 0x28);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid) != 0x0C);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid) != 0x10);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_status) != 0x14);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_utime) != 0x18);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_stime) != 0x1C);
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#ifdef CONFIG_X86_X32_ABI
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CHECK_CSI_OFFSET(_sigchld_x32);
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CHECK_CSI_SIZE (_sigchld_x32, 7*sizeof(int));
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/* no _sigchld_x32 in the generic siginfo_t */
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BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields._sigchld_x32._utime) != 0x18);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields._sigchld_x32._stime) != 0x20);
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#endif
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CHECK_CSI_OFFSET(_sigfault);
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CHECK_CSI_SIZE (_sigfault, 4*sizeof(int));
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CHECK_SI_SIZE (_sigfault, 8*sizeof(int));
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BUILD_BUG_ON(offsetof(siginfo_t, si_addr) != 0x10);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr) != 0x0C);
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BUILD_BUG_ON(offsetof(siginfo_t, si_addr_lsb) != 0x18);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr_lsb) != 0x10);
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BUILD_BUG_ON(offsetof(siginfo_t, si_lower) != 0x20);
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BUILD_BUG_ON(offsetof(siginfo_t, si_upper) != 0x28);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_lower) != 0x14);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_upper) != 0x18);
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BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x20);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pkey) != 0x14);
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CHECK_CSI_OFFSET(_sigpoll);
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CHECK_CSI_SIZE (_sigpoll, 2*sizeof(int));
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CHECK_SI_SIZE (_sigpoll, 4*sizeof(int));
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BUILD_BUG_ON(offsetof(siginfo_t, si_band) != 0x10);
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BUILD_BUG_ON(offsetof(siginfo_t, si_fd) != 0x18);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_band) != 0x0C);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_fd) != 0x10);
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CHECK_CSI_OFFSET(_sigsys);
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CHECK_CSI_SIZE (_sigsys, 3*sizeof(int));
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CHECK_SI_SIZE (_sigsys, 4*sizeof(int));
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BUILD_BUG_ON(offsetof(siginfo_t, si_call_addr) != 0x10);
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BUILD_BUG_ON(offsetof(siginfo_t, si_syscall) != 0x18);
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BUILD_BUG_ON(offsetof(siginfo_t, si_arch) != 0x1C);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_call_addr) != 0x0C);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_syscall) != 0x10);
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BUILD_BUG_ON(offsetof(compat_siginfo_t, si_arch) != 0x14);
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/* any new si_fields should be added here */
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}
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