Commit f71dd7dc authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

signal/ptrace: Add force_sig_ptrace_errno_trap and use it where needed 



There are so many places that build struct siginfo by hand that at
least one of them is bound to get it wrong.  A handful of cases in the
kernel arguably did just that when using the errno field of siginfo to
pass no errno values to userspace.  The usage is limited to a single
si_code so at least does not mess up anything else.

Encapsulate this questionable pattern in a helper function so
that the userspace ABI is preserved.

Update all of the places that use this pattern to use the new helper
function.

Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent 47355040

arch/arm/kernel/ptrace.c

+1 −7
Original line number Diff line number Diff line
@@ -390,7 +390,6 @@ static void ptrace_hbptriggered(struct perf_event *bp, 
	struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);

	long num;

	int i;

	siginfo_t info;



	for (i = 0; i < ARM_MAX_HBP_SLOTS; ++i)

		if (current->thread.debug.hbp[i] == bp)
@@ -398,12 +397,7 @@ static void ptrace_hbptriggered(struct perf_event *bp, 


	num = (i == ARM_MAX_HBP_SLOTS) ? 0 : ptrace_hbp_idx_to_num(i);



	info.si_signo	= SIGTRAP;

	info.si_errno	= (int)num;

	info.si_code	= TRAP_HWBKPT;

	info.si_addr	= (void __user *)(bkpt->trigger);



	force_sig_info(SIGTRAP, &info, current);

	force_sig_ptrace_errno_trap((int)num, (void __user *)(bkpt->trigger));

}



/*

arch/arm64/kernel/ptrace.c

+4 −2
Original line number Diff line number Diff line
@@ -190,21 +190,23 @@ static void ptrace_hbptriggered(struct perf_event *bp, 


#ifdef CONFIG_COMPAT

	if (is_compat_task()) {

		int si_errno = 0;

		int i;



		for (i = 0; i < ARM_MAX_BRP; ++i) {

			if (current->thread.debug.hbp_break[i] == bp) {

				info.si_errno = (i << 1) + 1;

				si_errno = (i << 1) + 1;

				break;

			}

		}



		for (i = 0; i < ARM_MAX_WRP; ++i) {

			if (current->thread.debug.hbp_watch[i] == bp) {

				info.si_errno = -((i << 1) + 1);

				si_errno = -((i << 1) + 1);

				break;

			}

		}

		force_sig_ptrace_errno_trap(si_errno, (void __user *)bkpt->trigger);

	}

#endif

	force_sig_info(SIGTRAP, &info, current);

arch/powerpc/kernel/process.c

+2 −7
Original line number Diff line number Diff line
@@ -603,19 +603,14 @@ EXPORT_SYMBOL(flush_all_to_thread); 
void do_send_trap(struct pt_regs *regs, unsigned long address,

		  unsigned long error_code, int breakpt)

{

	siginfo_t info;



	current->thread.trap_nr = TRAP_HWBKPT;

	if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,

			11, SIGSEGV) == NOTIFY_STOP)

		return;



	/* Deliver the signal to userspace */

	info.si_signo = SIGTRAP;

	info.si_errno = breakpt;	/* breakpoint or watchpoint id */

	info.si_code = TRAP_HWBKPT;

	info.si_addr = (void __user *)address;

	force_sig_info(SIGTRAP, &info, current);

	force_sig_ptrace_errno_trap(breakpt, /* breakpoint or watchpoint id */

				    (void __user *)address);

}

#else	/* !CONFIG_PPC_ADV_DEBUG_REGS */

void do_break (struct pt_regs *regs, unsigned long address,

arch/xtensa/kernel/ptrace.c

+1 −7
Original line number Diff line number Diff line
@@ -278,7 +278,6 @@ static void ptrace_hbptriggered(struct perf_event *bp, 
				struct pt_regs *regs)

{

	int i;

	siginfo_t info;

	struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);



	if (bp->attr.bp_type & HW_BREAKPOINT_X) {
@@ -293,12 +292,7 @@ static void ptrace_hbptriggered(struct perf_event *bp, 
		i = (i << 1) | 1;

	}



	info.si_signo = SIGTRAP;

	info.si_errno = i;

	info.si_code = TRAP_HWBKPT;

	info.si_addr = (void __user *)bkpt->address;



	force_sig_info(SIGTRAP, &info, current);

	force_sig_ptrace_errno_trap(i, (void __user *)bkpt->address);

}



static struct perf_event *ptrace_hbp_create(struct task_struct *tsk, int type)

include/linux/sched/signal.h

+2 −0
Original line number Diff line number Diff line
@@ -311,6 +311,8 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *); 
int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);

int force_sig_pkuerr(void __user *addr, u32 pkey);



int force_sig_ptrace_errno_trap(int errno, void __user *addr);



extern int send_sig_info(int, struct siginfo *, struct task_struct *);

extern int force_sigsegv(int, struct task_struct *);

extern int force_sig_info(int, struct siginfo *, struct task_struct *);

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