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authorOleg Nesterov <oleg@tv-sign.ru>2006-02-15 14:50:10 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-15 14:05:43 -0500
commit5ecfbae093f0c37311e89b29bfc0c9d586eace87 (patch)
treeeabd0a145af64e26c900578c95175ab313828661 /kernel
parentdadac81b1b86196fcc48fb87620403c4a7174f06 (diff)
[PATCH] fix zap_thread's ptrace related problems
1. The tracee can go from ptrace_stop() to do_signal_stop() after __ptrace_unlink(p). 2. It is unsafe to __ptrace_unlink(p) while p->parent may wait for tasklist_lock in ptrace_detach(). Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Christoph Hellwig <hch@lst.de> Cc: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/ptrace.c25
1 files changed, 15 insertions, 10 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index d2cf144d0af..d95a72c9279 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -72,8 +72,8 @@ void ptrace_untrace(task_t *child)
72 */ 72 */
73void __ptrace_unlink(task_t *child) 73void __ptrace_unlink(task_t *child)
74{ 74{
75 if (!child->ptrace) 75 BUG_ON(!child->ptrace);
76 BUG(); 76
77 child->ptrace = 0; 77 child->ptrace = 0;
78 if (!list_empty(&child->ptrace_list)) { 78 if (!list_empty(&child->ptrace_list)) {
79 list_del_init(&child->ptrace_list); 79 list_del_init(&child->ptrace_list);
@@ -184,22 +184,27 @@ bad:
184 return retval; 184 return retval;
185} 185}
186 186
187void __ptrace_detach(struct task_struct *child, unsigned int data)
188{
189 child->exit_code = data;
190 /* .. re-parent .. */
191 __ptrace_unlink(child);
192 /* .. and wake it up. */
193 if (child->exit_state != EXIT_ZOMBIE)
194 wake_up_process(child);
195}
196
187int ptrace_detach(struct task_struct *child, unsigned int data) 197int ptrace_detach(struct task_struct *child, unsigned int data)
188{ 198{
189 if (!valid_signal(data)) 199 if (!valid_signal(data))
190 return -EIO; 200 return -EIO;
191 201
192 /* Architecture-specific hardware disable .. */ 202 /* Architecture-specific hardware disable .. */
193 ptrace_disable(child); 203 ptrace_disable(child);
194 204
195 /* .. re-parent .. */
196 child->exit_code = data;
197
198 write_lock_irq(&tasklist_lock); 205 write_lock_irq(&tasklist_lock);
199 __ptrace_unlink(child); 206 if (child->ptrace)
200 /* .. and wake it up. */ 207 __ptrace_detach(child, data);
201 if (child->exit_state != EXIT_ZOMBIE)
202 wake_up_process(child);
203 write_unlock_irq(&tasklist_lock); 208 write_unlock_irq(&tasklist_lock);
204 209
205 return 0; 210 return 0;