tracing: fix the "old_pid" usage in trace_sched_process_exec()

PATCH In review Oleg Nesterov 2 participants 4 messages Mar 30, 2012 – Mar 31, 2012

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VFS Tracing exec and binfmt

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Oleg Nesterov

author

2012-03-30 16:34 UTC #0 lore raw

PATCH 1/1 tracing: fix the "old_pid" usage in trace_sched_process_exec()

1. TRACE_EVENT(sched_process_exec) forgets to actually use the old pid argument, it sets ->old_pid = p->pid.

2. search_binary_handler() uses the wrong pid number. tracepoint needs the global pid_t from the root namespace, while old_pid is the virtual pid number as it seen by the tracer/parent.

With this patch we have two pid_t's in search_binary_handler(), not really nice. Perhaps we should switch to "struct pid*", but in this case it would be better to cleanup the current code first and move the "depth == 0" code outside.

Signed-off-by Oleg Nesterov <[email protected]>

---
 fs/exec.c                    |    7 ++++---
 include/trace/events/sched.h |    2 +-
 2 files changed, 5 insertions(+), 4 deletions(-)

fs/exec.c +4 -3

index e48c66e..91db3e8 100644
@@ -1372,7 +1372,7 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 	unsigned int depth = bprm->recursion_depth;
 	int try,retval;
 	struct linux_binfmt *fmt;
-	pid_t old_pid;
+	pid_t old_pid, old_vpid;
 
 	retval = security_bprm_check(bprm);
 	if (retval)

@@ -1383,8 +1383,9 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 		return retval;
 
 	/* Need to fetch pid before load_binary changes it */
+	old_pid = current->pid;
 	rcu_read_lock();
-	old_pid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
+	old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
 	rcu_read_unlock();
 
 	retval = -ENOENT;

@@ -1407,7 +1408,7 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 			if (retval >= 0) {
 				if (depth == 0) {
 					trace_sched_process_exec(current, old_pid, bprm);
-					ptrace_event(PTRACE_EVENT_EXEC, old_pid);
+					ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
 				}
 				put_binfmt(fmt);
 				allow_write_access(bprm->file);

include/trace/events/sched.h +1 -1

index e61ddfe..2f10e81 100644
@@ -295,7 +295,7 @@ TRACE_EVENT(sched_process_exec,
 	TP_fast_assign(
 		__assign_str(filename, bprm->filename);
 		__entry->pid		= p->pid;
-		__entry->old_pid	= p->pid;
+		__entry->old_pid	= old_pid;
 	),
 
 	TP_printk("filename=%s pid=%d old_pid=%d", __get_str(filename),

Signature · 1 line

1.5.5.1

Oleg Nesterov

author

2012-03-30 16:37 UTC #1 lore raw

Quoted 7 lines · Oleg Nesterov

1. TRACE_EVENT(sched_process_exec) forgets to actually use the old pid argument, it sets ->old_pid = p->pid.
2. search_binary_handler() uses the wrong pid number. tracepoint needs the global pid_t from the root namespace, while old_pid is the virtual pid number as it seen by the tracer/parent.

Not really serious, but probably makes sense for 3.4. This fixes the recently merged 4ff16c25e2cc48cbe6956e356c38a25ac063a64d "tracepoint, vfs, sched: Add exec() tracepoint"

Oleg.

Ingo Molnar

2012-03-31 09:52 UTC #2 lore raw

Quoted 5 lines · Oleg Nesterov

Quoted 4 lines · Oleg Nesterov
1. TRACE_EVENT(sched_process_exec) forgets to actually use the old pid argument, it sets ->old_pid = p->pid.

Quoted 7 lines

Quoted 3 lines
2. search_binary_handler() uses the wrong pid number. tracepoint needs the global pid_t from the root namespace, while old_pid is the virtual pid number as it seen by the tracer/parent.
Not really serious, but probably makes sense for 3.4. This fixes the recently merged 4ff16c25e2cc48cbe6956e356c38a25ac063a64d "tracepoint, vfs, sched: Add exec() tracepoint"

Thanks Oleg - will queue your fix up in tip:perf/urgent.

Thanks,

Ingo

tip-bot for Oleg Nesterov

author

2012-03-31 17:21 UTC #3 lore raw

[tip:perf/urgent] tracing, sched, vfs: Fix 'old_pid' usage in trace_sched_process_exec()

In reply to Oleg Nesterov

Commit-ID:  6308191f6f55d3629c7dbe72dfb856ad9fa560fd
Gitweb:     http://git.kernel.org/tip/6308191f6f55d3629c7dbe72dfb856ad9fa560fd
Author:     Oleg Nesterov <[email protected]>
AuthorDate: Fri, 30 Mar 2012 18:26:36 +0200
Committer:  Ingo Molnar <[email protected]>
CommitDate: Sat, 31 Mar 2012 11:53:22 +0200

tracing, sched, vfs: Fix 'old_pid' usage in trace_sched_process_exec()

1. TRACE_EVENT(sched_process_exec) forgets to actually use the old pid argument, it sets ->old_pid = p->pid.

2. search_binary_handler() uses the wrong pid number. tracepoint needs the global pid_t from the root namespace, while old_pid is the virtual pid number as it seen by the tracer/parent.

Signed-off-by Oleg Nesterov <[email protected]>

Cc David Smith <[email protected]>

Cc Peter Zijlstra <[email protected]>

Cc Steven Rostedt <[email protected]>

Cc Denys Vlasenko <[email protected]>

Link http://lkml.kernel.org/r/[email protected] open here

Signed-off-by Ingo Molnar <[email protected]>

---
 fs/exec.c                    |    7 ++++---
 include/trace/events/sched.h |    2 +-
 2 files changed, 5 insertions(+), 4 deletions(-)

fs/exec.c +4 -3

index 23559c2..644f6c4 100644
@@ -1370,7 +1370,7 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 	unsigned int depth = bprm->recursion_depth;
 	int try,retval;
 	struct linux_binfmt *fmt;
-	pid_t old_pid;
+	pid_t old_pid, old_vpid;
 
 	retval = security_bprm_check(bprm);
 	if (retval)

@@ -1381,8 +1381,9 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 		return retval;
 
 	/* Need to fetch pid before load_binary changes it */
+	old_pid = current->pid;
 	rcu_read_lock();
-	old_pid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
+	old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
 	rcu_read_unlock();
 
 	retval = -ENOENT;

@@ -1405,7 +1406,7 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 			if (retval >= 0) {
 				if (depth == 0) {
 					trace_sched_process_exec(current, old_pid, bprm);
-					ptrace_event(PTRACE_EVENT_EXEC, old_pid);
+					ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
 				}
 				put_binfmt(fmt);
 				allow_write_access(bprm->file);

include/trace/events/sched.h +1 -1

index fbc7b1a..ea7a203 100644
@@ -295,7 +295,7 @@ TRACE_EVENT(sched_process_exec,
 	TP_fast_assign(
 		__assign_str(filename, bprm->filename);
 		__entry->pid		= p->pid;
-		__entry->old_pid	= p->pid;
+		__entry->old_pid	= old_pid;
 	),
 
 	TP_printk("filename=%s pid=%d old_pid=%d", __get_str(filename),