signal: Don't use structure initializers for struct siginfo

The siginfo structure has all manners of holes with the result that a
structure initializer is not guaranteed to initialize all of the bits.
As we have to copy the structure to userspace don't even try to use
a structure initializer.  Instead use clear_siginfo followed by initializing
selected fields.  This gives a guarantee that uninitialized kernel memory
is not copied to userspace.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

3 files changed, 43 insertions, 31 deletions

diff --git a/arch/tile/kernel/single_step.c b/arch/tile/kernel/single_step.c
index de3eae813e52..479d8033a801 100644
--- a/arch/tile/kernel/single_step.c
+++ b/arch/tile/kernel/single_step.c
@@ -163,11 +163,13 @@ static tilepro_bundle_bits rewrite_load_store_unaligned(
 	 * actual bad address in an SPR, which it doesn't.
 	 */
 	if (align_ctl == 0) {
-		siginfo_t info = {
-			.si_signo = SIGBUS,
-			.si_code = BUS_ADRALN,
-			.si_addr = addr
-		};
+		siginfo_t info;
+
+		clear_siginfo(&info);
+		info.si_signo = SIGBUS;
+		info.si_code = BUS_ADRALN;
+		info.si_addr = addr;
+
 		trace_unhandled_signal("unaligned trap", regs,
 				       (unsigned long)addr, SIGBUS);
 		force_sig_info(info.si_signo, &info, current);
@@ -210,11 +212,13 @@ static tilepro_bundle_bits rewrite_load_store_unaligned(
 	}
 
 	if (err) {
-		siginfo_t info = {
-			.si_signo = SIGBUS,
-			.si_code = BUS_ADRALN,
-			.si_addr = addr
-		};
+		siginfo_t info;
+
+		clear_siginfo(&info);
+		info.si_signo = SIGBUS;
+		info.si_code = BUS_ADRALN;
+		info.si_addr = addr;
+
 		trace_unhandled_signal("bad address for unaligned fixup", regs,
 				       (unsigned long)addr, SIGBUS);
 		force_sig_info(info.si_signo, &info, current);
diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c
index 9b08c6055f15..83a7186198d7 100644
--- a/arch/tile/kernel/traps.c
+++ b/arch/tile/kernel/traps.c
@@ -256,12 +256,14 @@ static int do_bpt(struct pt_regs *regs)
 void __kprobes do_trap(struct pt_regs *regs, int fault_num,
 		       unsigned long reason)
 {
-	siginfo_t info = { 0 };
+	siginfo_t info;
 	int signo, code;
 	unsigned long address = 0;
 	tile_bundle_bits instr;
 	int is_kernel = !user_mode(regs);
 
+	clear_siginfo(&info);
+
 	/* Handle breakpoints, etc. */
 	if (is_kernel && fault_num == INT_ILL && do_bpt(regs))
 		return;
diff --git a/arch/tile/kernel/unaligned.c b/arch/tile/kernel/unaligned.c
index 8149c38f67b6..77a0b6b6a2a1 100644
--- a/arch/tile/kernel/unaligned.c
+++ b/arch/tile/kernel/unaligned.c
@@ -980,11 +980,13 @@ void jit_bundle_gen(struct pt_regs *regs, tilegx_bundle_bits bundle,
 	}
 
 	if ((align_ctl == 0) || unexpected) {
-		siginfo_t info = {
-			.si_signo = SIGBUS,
-			.si_code = BUS_ADRALN,
-			.si_addr = (unsigned char __user *)0
-		};
+		siginfo_t info;
+
+		clear_siginfo(&info);
+		info.si_signo = SIGBUS;
+		info.si_code = BUS_ADRALN;
+		info.si_addr = (unsigned char __user *)0;
+
 		if (unaligned_printk)
 			pr_info("Unalign bundle: unexp @%llx, %llx\n",
 				(unsigned long long)regs->pc,
@@ -1396,11 +1398,12 @@ void jit_bundle_gen(struct pt_regs *regs, tilegx_bundle_bits bundle,
 				      &frag, sizeof(frag));
 		if (status) {
 			/* Fail to copy JIT into user land. send SIGSEGV. */
-			siginfo_t info = {
-				.si_signo = SIGSEGV,
-				.si_code = SEGV_MAPERR,
-				.si_addr = (void __user *)&jit_code_area[idx]
-			};
+			siginfo_t info;
+
+			clear_siginfo(&info);
+			info.si_signo = SIGSEGV;
+			info.si_code = SEGV_MAPERR;
+			info.si_addr = (void __user *)&jit_code_area[idx];
 
 			pr_warn("Unalign fixup: pid=%d %s jit_code_area=%llx\n",
 				current->pid, current->comm,
@@ -1511,11 +1514,12 @@ void do_unaligned(struct pt_regs *regs, int vecnum)
 	 * If so, we will trigger SIGBUS.
 	 */
 	if ((regs->sp & 0x7) || (regs->ex1) || (align_ctl < 0)) {
-		siginfo_t info = {
-			.si_signo = SIGBUS,
-			.si_code = BUS_ADRALN,
-			.si_addr = (unsigned char __user *)0
-		};
+		siginfo_t info;
+
+		clear_siginfo(&info);
+		info.si_signo = SIGBUS;
+		info.si_code = BUS_ADRALN;
+		info.si_addr = (unsigned char __user *)0;
 
 		if (unaligned_printk)
 			pr_info("Unalign fixup: %d %llx @%llx\n",
@@ -1535,11 +1539,13 @@ void do_unaligned(struct pt_regs *regs, int vecnum)
 	pc = (tilegx_bundle_bits __user *)(regs->pc);
 	if (get_user(bundle, pc) != 0) {
 		/* Probably never be here since pc is valid user address.*/
-		siginfo_t info = {
-			.si_signo = SIGSEGV,
-			.si_code = SEGV_MAPERR,
-			.si_addr = (void __user *)pc
-		};
+		siginfo_t info;
+
+		clear_siginfo(&info);
+		info.si_signo = SIGSEGV;
+		info.si_code = SEGV_MAPERR;
+		info.si_addr = (void __user *)pc;
+
 		pr_err("Couldn't read instruction at %p trying to step\n", pc);
 		trace_unhandled_signal("segfault in unalign fixup", regs,
 				       (unsigned long)info.si_addr, SIGSEGV);