signal: Ensure every siginfo we send has all bits initialized

Call clear_siginfo to ensure every stack allocated siginfo is properly
initialized before being passed to the signal sending functions.

Note: It is not safe to depend on C initializers to initialize struct
siginfo on the stack because C is allowed to skip holes when
initializing a structure.

The initialization of struct siginfo in tracehook_report_syscall_exit
was moved from the helper user_single_step_siginfo into
tracehook_report_syscall_exit itself, to make it clear that the local
variable siginfo gets fully initialized.

In a few cases the scope of struct siginfo has been reduced to make it
clear that siginfo siginfo is not used on other paths in the function
in which it is declared.

Instances of using memset to initialize siginfo have been replaced
with calls clear_siginfo for clarity.

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

7 files changed, 29 insertions, 0 deletions

diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 454a8af..2219e55 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -520,6 +520,7 @@ static void stack_unaligned(unsigned long sp)
 {
 	siginfo_t info;
 
+	clear_siginfo(&info);
 	info.si_signo = SIGBUS;
 	info.si_errno = 0;
 	info.si_code = BUS_ADRALN;
diff --git a/arch/sparc/kernel/sys_sparc_32.c b/arch/sparc/kernel/sys_sparc_32.c
index e8c3cb6..00f6353 100644
--- a/arch/sparc/kernel/sys_sparc_32.c
+++ b/arch/sparc/kernel/sys_sparc_32.c
@@ -152,6 +152,7 @@ sparc_breakpoint (struct pt_regs *regs)
 #ifdef DEBUG_SPARC_BREAKPOINT
         printk ("TRAP: Entering kernel PC=%x, nPC=%x\n", regs->pc, regs->npc);
 #endif
+	clear_siginfo(&info);
 	info.si_signo = SIGTRAP;
 	info.si_errno = 0;
 	info.si_code = TRAP_BRKPT;
diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c
index 33cd35b..03e5222 100644
--- a/arch/sparc/kernel/traps_32.c
+++ b/arch/sparc/kernel/traps_32.c
@@ -104,6 +104,7 @@ void do_hw_interrupt(struct pt_regs *regs, unsigned long type)
 	if(regs->psr & PSR_PS)
 		die_if_kernel("Kernel bad trap", regs);
 
+	clear_siginfo(&info);
 	info.si_signo = SIGILL;
 	info.si_errno = 0;
 	info.si_code = ILL_ILLTRP;
@@ -124,6 +125,7 @@ void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned lon
 	       regs->pc, *(unsigned long *)regs->pc);
 #endif
 
+	clear_siginfo(&info);
 	info.si_signo = SIGILL;
 	info.si_errno = 0;
 	info.si_code = ILL_ILLOPC;
@@ -139,6 +141,7 @@ void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long n
 
 	if(psr & PSR_PS)
 		die_if_kernel("Penguin instruction from Penguin mode??!?!", regs);
+	clear_siginfo(&info);
 	info.si_signo = SIGILL;
 	info.si_errno = 0;
 	info.si_code = ILL_PRVOPC;
@@ -165,6 +168,7 @@ void do_memaccess_unaligned(struct pt_regs *regs, unsigned long pc, unsigned lon
 	instruction_dump ((unsigned long *) regs->pc);
 	printk ("do_MNA!\n");
 #endif
+	clear_siginfo(&info);
 	info.si_signo = SIGBUS;
 	info.si_errno = 0;
 	info.si_code = BUS_ADRALN;
@@ -303,6 +307,7 @@ void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 	}
 
 	fsr = fpt->thread.fsr;
+	clear_siginfo(&info);
 	info.si_signo = SIGFPE;
 	info.si_errno = 0;
 	info.si_addr = (void __user *)pc;
@@ -336,6 +341,7 @@ void handle_tag_overflow(struct pt_regs *regs, unsigned long pc, unsigned long n
 
 	if(psr & PSR_PS)
 		die_if_kernel("Penguin overflow trap from kernel mode", regs);
+	clear_siginfo(&info);
 	info.si_signo = SIGEMT;
 	info.si_errno = 0;
 	info.si_code = EMT_TAGOVF;
@@ -365,6 +371,7 @@ void handle_reg_access(struct pt_regs *regs, unsigned long pc, unsigned long npc
 	printk("Register Access Exception at PC %08lx NPC %08lx PSR %08lx\n",
 	       pc, npc, psr);
 #endif
+	clear_siginfo(&info);
 	info.si_signo = SIGBUS;
 	info.si_errno = 0;
 	info.si_code = BUS_OBJERR;
@@ -378,6 +385,7 @@ void handle_cp_disabled(struct pt_regs *regs, unsigned long pc, unsigned long np
 {
 	siginfo_t info;
 
+	clear_siginfo(&info);
 	info.si_signo = SIGILL;
 	info.si_errno = 0;
 	info.si_code = ILL_COPROC;
@@ -395,6 +403,7 @@ void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long n
 	printk("Co-Processor Exception at PC %08lx NPC %08lx PSR %08lx\n",
 	       pc, npc, psr);
 #endif
+	clear_siginfo(&info);
 	info.si_signo = SIGILL;
 	info.si_errno = 0;
 	info.si_code = ILL_COPROC;
@@ -408,6 +417,7 @@ void handle_hw_divzero(struct pt_regs *regs, unsigned long pc, unsigned long npc
 {
 	siginfo_t info;
 
+	clear_siginfo(&info);
 	info.si_signo = SIGFPE;
 	info.si_errno = 0;
 	info.si_code = FPE_INTDIV;
diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
index e81072a..b485b49 100644
--- a/arch/sparc/kernel/traps_64.c
+++ b/arch/sparc/kernel/traps_64.c
@@ -107,6 +107,7 @@ void bad_trap(struct pt_regs *regs, long lvl)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
+	clear_siginfo(&info);
 	info.si_signo = SIGILL;
 	info.si_errno = 0;
 	info.si_code = ILL_ILLTRP;
@@ -206,6 +207,7 @@ void spitfire_insn_access_exception(struct pt_regs *regs, unsigned long sfsr, un
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
+	clear_siginfo(&info);
 	info.si_signo = SIGSEGV;
 	info.si_errno = 0;
 	info.si_code = SEGV_MAPERR;
@@ -247,6 +249,7 @@ void sun4v_insn_access_exception(struct pt_regs *regs, unsigned long addr, unsig
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
+	clear_siginfo(&info);
 	info.si_signo = SIGSEGV;
 	info.si_errno = 0;
 	info.si_code = SEGV_MAPERR;
@@ -338,6 +341,7 @@ void spitfire_data_access_exception(struct pt_regs *regs, unsigned long sfsr, un
 	if (is_no_fault_exception(regs))
 		return;
 
+	clear_siginfo(&info);
 	info.si_signo = SIGSEGV;
 	info.si_errno = 0;
 	info.si_code = SEGV_MAPERR;
@@ -595,6 +599,7 @@ static void spitfire_ue_log(unsigned long afsr, unsigned long afar, unsigned lon
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
+	clear_siginfo(&info);
 	info.si_signo = SIGBUS;
 	info.si_errno = 0;
 	info.si_code = BUS_OBJERR;
@@ -2211,6 +2216,7 @@ bool sun4v_nonresum_error_user_handled(struct pt_regs *regs,
 				addr += PAGE_SIZE;
 			}
 		}
+		clear_siginfo(&info);
 		info.si_signo = SIGKILL;
 		info.si_errno = 0;
 		info.si_trapno = 0;
@@ -2221,6 +2227,7 @@ bool sun4v_nonresum_error_user_handled(struct pt_regs *regs,
 	if (attrs & SUN4V_ERR_ATTRS_PIO) {
 		siginfo_t info;
 
+		clear_siginfo(&info);
 		info.si_signo = SIGBUS;
 		info.si_code = BUS_ADRERR;
 		info.si_addr = (void __user *)sun4v_get_vaddr(regs);
@@ -2368,6 +2375,7 @@ static void do_fpe_common(struct pt_regs *regs)
 			regs->tpc &= 0xffffffff;
 			regs->tnpc &= 0xffffffff;
 		}
+		clear_siginfo(&info);
 		info.si_signo = SIGFPE;
 		info.si_errno = 0;
 		info.si_addr = (void __user *)regs->tpc;
@@ -2440,6 +2448,7 @@ void do_tof(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
+	clear_siginfo(&info);
 	info.si_signo = SIGEMT;
 	info.si_errno = 0;
 	info.si_code = EMT_TAGOVF;
@@ -2465,6 +2474,7 @@ void do_div0(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
+	clear_siginfo(&info);
 	info.si_signo = SIGFPE;
 	info.si_errno = 0;
 	info.si_code = FPE_INTDIV;
@@ -2666,6 +2676,7 @@ void do_illegal_instruction(struct pt_regs *regs)
 			}
 		}
 	}
+	clear_siginfo(&info);
 	info.si_signo = SIGILL;
 	info.si_errno = 0;
 	info.si_code = ILL_ILLOPC;
@@ -2692,6 +2703,7 @@ void mem_address_unaligned(struct pt_regs *regs, unsigned long sfar, unsigned lo
 	if (is_no_fault_exception(regs))
 		return;
 
+	clear_siginfo(&info);
 	info.si_signo = SIGBUS;
 	info.si_errno = 0;
 	info.si_code = BUS_ADRALN;
@@ -2717,6 +2729,7 @@ void sun4v_do_mna(struct pt_regs *regs, unsigned long addr, unsigned long type_c
 	if (is_no_fault_exception(regs))
 		return;
 
+	clear_siginfo(&info);
 	info.si_signo = SIGBUS;
 	info.si_errno = 0;
 	info.si_code = BUS_ADRALN;
@@ -2785,6 +2798,7 @@ void do_privop(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
+	clear_siginfo(&info);
 	info.si_signo = SIGILL;
 	info.si_errno = 0;
 	info.si_code = ILL_PRVOPC;
diff --git a/arch/sparc/kernel/unaligned_32.c b/arch/sparc/kernel/unaligned_32.c
index 7642d7e..0e4cf721 100644
--- a/arch/sparc/kernel/unaligned_32.c
+++ b/arch/sparc/kernel/unaligned_32.c
@@ -313,6 +313,7 @@ static void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
 {
 	siginfo_t info;
 
+	clear_siginfo(&info);
 	info.si_signo = SIGBUS;
 	info.si_errno = 0;
 	info.si_code = BUS_ADRALN;
diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
index a8103a8..2deb586 100644
--- a/arch/sparc/mm/fault_32.c
+++ b/arch/sparc/mm/fault_32.c
@@ -129,6 +129,7 @@ static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 {
 	siginfo_t info;
 
+	clear_siginfo(&info);
 	info.si_signo = sig;
 	info.si_code = code;
 	info.si_errno = 0;
diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index 41363f4..46ccff9 100644
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -172,6 +172,7 @@ static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 	unsigned long addr;
 	siginfo_t info;
 
+	clear_siginfo(&info);
 	info.si_code = code;
 	info.si_signo = sig;
 	info.si_errno = 0;