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Commit f6a01549 authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

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: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent 859d880c

arch/x86/kernel/signal_compat.c

+65 −0
Original line number Diff line number Diff line
@@ -43,6 +43,13 @@ static inline void signal_compat_build_tests(void) 
	BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields) != 3 * sizeof(int));

#define CHECK_CSI_OFFSET(name)	  BUILD_BUG_ON(_sifields_offset != offsetof(compat_siginfo_t, _sifields.name))



	BUILD_BUG_ON(offsetof(siginfo_t, si_signo) != 0);

	BUILD_BUG_ON(offsetof(siginfo_t, si_errno) != 4);

	BUILD_BUG_ON(offsetof(siginfo_t, si_code)  != 8);



	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_signo) != 0);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_errno) != 4);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_code)  != 8);

	 /*

	 * Ensure that the size of each si_field never changes.

	 * If it does, it is a sign that the
@@ -63,36 +70,94 @@ static inline void signal_compat_build_tests(void) 
	CHECK_CSI_SIZE  (_kill, 2*sizeof(int));

	CHECK_SI_SIZE   (_kill, 2*sizeof(int));



	BUILD_BUG_ON(offsetof(siginfo_t, si_pid) != 0x10);

	BUILD_BUG_ON(offsetof(siginfo_t, si_uid) != 0x14);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid) != 0xC);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid) != 0x10);



	CHECK_CSI_OFFSET(_timer);

	CHECK_CSI_SIZE  (_timer, 3*sizeof(int));

	CHECK_SI_SIZE   (_timer, 6*sizeof(int));



	BUILD_BUG_ON(offsetof(siginfo_t, si_tid)     != 0x10);

	BUILD_BUG_ON(offsetof(siginfo_t, si_overrun) != 0x14);

	BUILD_BUG_ON(offsetof(siginfo_t, si_value)   != 0x18);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_tid)     != 0x0C);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_overrun) != 0x10);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_value)   != 0x14);



	CHECK_CSI_OFFSET(_rt);

	CHECK_CSI_SIZE  (_rt, 3*sizeof(int));

	CHECK_SI_SIZE   (_rt, 4*sizeof(int));



	BUILD_BUG_ON(offsetof(siginfo_t, si_pid)   != 0x10);

	BUILD_BUG_ON(offsetof(siginfo_t, si_uid)   != 0x14);

	BUILD_BUG_ON(offsetof(siginfo_t, si_value) != 0x18);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid)   != 0x0C);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid)   != 0x10);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_value) != 0x14);



	CHECK_CSI_OFFSET(_sigchld);

	CHECK_CSI_SIZE  (_sigchld, 5*sizeof(int));

	CHECK_SI_SIZE   (_sigchld, 8*sizeof(int));



	BUILD_BUG_ON(offsetof(siginfo_t, si_pid)    != 0x10);

	BUILD_BUG_ON(offsetof(siginfo_t, si_uid)    != 0x14);

	BUILD_BUG_ON(offsetof(siginfo_t, si_status) != 0x18);

	BUILD_BUG_ON(offsetof(siginfo_t, si_utime)  != 0x20);

	BUILD_BUG_ON(offsetof(siginfo_t, si_stime)  != 0x28);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid)    != 0x0C);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid)    != 0x10);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_status) != 0x14);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_utime)  != 0x18);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_stime)  != 0x1C);



#ifdef CONFIG_X86_X32_ABI

	CHECK_CSI_OFFSET(_sigchld_x32);

	CHECK_CSI_SIZE  (_sigchld_x32, 7*sizeof(int));

	/* no _sigchld_x32 in the generic siginfo_t */

	BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields._sigchld_x32._utime)  != 0x18);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields._sigchld_x32._stime)  != 0x20);

#endif



	CHECK_CSI_OFFSET(_sigfault);

	CHECK_CSI_SIZE  (_sigfault, 4*sizeof(int));

	CHECK_SI_SIZE   (_sigfault, 8*sizeof(int));



	BUILD_BUG_ON(offsetof(siginfo_t, si_addr) != 0x10);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr) != 0x0C);



	BUILD_BUG_ON(offsetof(siginfo_t, si_addr_lsb) != 0x18);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr_lsb) != 0x10);



	BUILD_BUG_ON(offsetof(siginfo_t, si_lower) != 0x20);

	BUILD_BUG_ON(offsetof(siginfo_t, si_upper) != 0x28);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_lower) != 0x14);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_upper) != 0x18);



	BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x20);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pkey) != 0x14);



	CHECK_CSI_OFFSET(_sigpoll);

	CHECK_CSI_SIZE  (_sigpoll, 2*sizeof(int));

	CHECK_SI_SIZE   (_sigpoll, 4*sizeof(int));



	BUILD_BUG_ON(offsetof(siginfo_t, si_band)   != 0x10);

	BUILD_BUG_ON(offsetof(siginfo_t, si_fd)     != 0x18);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_band) != 0x0C);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_fd)   != 0x10);



	CHECK_CSI_OFFSET(_sigsys);

	CHECK_CSI_SIZE  (_sigsys, 3*sizeof(int));

	CHECK_SI_SIZE   (_sigsys, 4*sizeof(int));



	BUILD_BUG_ON(offsetof(siginfo_t, si_call_addr) != 0x10);

	BUILD_BUG_ON(offsetof(siginfo_t, si_syscall)   != 0x18);

	BUILD_BUG_ON(offsetof(siginfo_t, si_arch)      != 0x1C);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_call_addr) != 0x0C);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_syscall)   != 0x10);

	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_arch)      != 0x14);



	/* any new si_fields should be added here */

}