Commit 0b44bf9a authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

signal: Simplify and fix kdb_send_sig 



- Rename from kdb_send_sig_info to kdb_send_sig
  As there is no meaningful siginfo sent

- Use SEND_SIG_PRIV instead of generating a siginfo for a kdb
  signal.  The generated siginfo had a bogus rationale and was
  not correct in the face of pid namespaces.  SEND_SIG_PRIV
  is simpler and actually correct.

- As the code grabs siglock just send the signal with siglock
  held instead of dropping siglock and attempting to grab it again.

- Move the sig_valid test into kdb_kill where it can generate
  a good error message.

Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
parent 30a7acd5

kernel/debug/kdb/kdb_main.c

+2 −8
Original line number Diff line number Diff line
@@ -2441,7 +2441,6 @@ static int kdb_kill(int argc, const char **argv) 
	long sig, pid;

	char *endp;

	struct task_struct *p;

	struct siginfo info;



	if (argc != 2)

		return KDB_ARGCOUNT;
@@ -2449,7 +2448,7 @@ static int kdb_kill(int argc, const char **argv) 
	sig = simple_strtol(argv[1], &endp, 0);

	if (*endp)

		return KDB_BADINT;

	if (sig >= 0) {

	if ((sig >= 0) || !valid_signal(-sig)) {

		kdb_printf("Invalid signal parameter.<-signal>\n");

		return 0;

	}
@@ -2470,12 +2469,7 @@ static int kdb_kill(int argc, const char **argv) 
		return 0;

	}

	p = p->group_leader;

	info.si_signo = sig;

	info.si_errno = 0;

	info.si_code = SI_USER;

	info.si_pid = pid;  /* same capabilities as process being signalled */

	info.si_uid = 0;    /* kdb has root authority */

	kdb_send_sig_info(p, &info);

	kdb_send_sig(p, sig);

	return 0;

}

kernel/debug/kdb/kdb_private.h

+1 −1
Original line number Diff line number Diff line
@@ -208,7 +208,7 @@ extern unsigned long kdb_task_state(const struct task_struct *p, 
extern void kdb_ps_suppressed(void);

extern void kdb_ps1(const struct task_struct *p);

extern void kdb_print_nameval(const char *name, unsigned long val);

extern void kdb_send_sig_info(struct task_struct *p, struct siginfo *info);

extern void kdb_send_sig(struct task_struct *p, int sig);

extern void kdb_meminfo_proc_show(void);

extern char *kdb_getstr(char *, size_t, const char *);

extern void kdb_gdb_state_pass(char *buf);

kernel/signal.c

+7 −7
Original line number Diff line number Diff line
@@ -3684,26 +3684,25 @@ void __init signals_init(void) 
#ifdef CONFIG_KGDB_KDB

#include <linux/kdb.h>

/*

 * kdb_send_sig_info - Allows kdb to send signals without exposing

 * kdb_send_sig - Allows kdb to send signals without exposing

 * signal internals.  This function checks if the required locks are

 * available before calling the main signal code, to avoid kdb

 * deadlocks.

 */

void

kdb_send_sig_info(struct task_struct *t, struct siginfo *info)

void kdb_send_sig(struct task_struct *t, int sig)

{

	static struct task_struct *kdb_prev_t;

	int sig, new_t;

	int new_t, ret;

	if (!spin_trylock(&t->sighand->siglock)) {

		kdb_printf("Can't do kill command now.\n"

			   "The sigmask lock is held somewhere else in "

			   "kernel, try again later\n");

		return;

	}

	spin_unlock(&t->sighand->siglock);

	new_t = kdb_prev_t != t;

	kdb_prev_t = t;

	if (t->state != TASK_RUNNING && new_t) {

		spin_unlock(&t->sighand->siglock);

		kdb_printf("Process is not RUNNING, sending a signal from "

			   "kdb risks deadlock\n"

			   "on the run queue locks. "
@@ -3712,8 +3711,9 @@ kdb_send_sig_info(struct task_struct *t, struct siginfo *info) 
			   "the deadlock.\n");

		return;

	}

	sig = info->si_signo;

	if (send_sig_info(sig, info, t))

	ret = send_signal(sig, SEND_SIG_PRIV, t, false);

	spin_unlock(&t->sighand->siglock);

	if (ret)

		kdb_printf("Fail to deliver Signal %d to process %d.\n",

			   sig, t->pid);

	else

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