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Merge tag 'trace-v6.0-rc1-2' of git://git.kernel.org/pub/scm/linux/ke…
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…rnel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "Various fixes for tracing:

   - Fix a return value of traceprobe_parse_event_name()

   - Fix NULL pointer dereference from failed ftrace enabling

   - Fix NULL pointer dereference when asking for registers from eprobes

   - Make eprobes consistent with kprobes/uprobes, filters and
     histograms"

* tag 'trace-v6.0-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Have filter accept "common_cpu" to be consistent
  tracing/probes: Have kprobes and uprobes use $COMM too
  tracing/eprobes: Have event probes be consistent with kprobes and uprobes
  tracing/eprobes: Fix reading of string fields
  tracing/eprobes: Do not hardcode $comm as a string
  tracing/eprobes: Do not allow eprobes to use $stack, or % for regs
  ftrace: Fix NULL pointer dereference in is_ftrace_trampoline when ftrace is dead
  tracing/perf: Fix double put of trace event when init fails
  tracing: React to error return from traceprobe_parse_event_name()
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@torvalds
torvalds committed Aug 21, 2022
2 parents e3f259d + b238057 commit 7fb312d
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Showing 5 changed files with 119 additions and 21 deletions.
10 changes: 10 additions & 0 deletions kernel/trace/ftrace.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2974,6 +2974,16 @@ int ftrace_startup(struct ftrace_ops *ops, int command)

ftrace_startup_enable(command);

/*
* If ftrace is in an undefined state, we just remove ops from list
* to prevent the NULL pointer, instead of totally rolling it back and
* free trampoline, because those actions could cause further damage.
*/
if (unlikely(ftrace_disabled)) {
__unregister_ftrace_function(ops);
return -ENODEV;
}

ops->flags &= ~FTRACE_OPS_FL_ADDING;

return 0;
Expand Down
93 changes: 86 additions & 7 deletions kernel/trace/trace_eprobe.c
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Original file line number Diff line number Diff line change
Expand Up @@ -227,6 +227,7 @@ static int trace_eprobe_tp_arg_update(struct trace_eprobe *ep, int i)
struct probe_arg *parg = &ep->tp.args[i];
struct ftrace_event_field *field;
struct list_head *head;
int ret = -ENOENT;

head = trace_get_fields(ep->event);
list_for_each_entry(field, head, link) {
Expand All @@ -236,9 +237,20 @@ static int trace_eprobe_tp_arg_update(struct trace_eprobe *ep, int i)
return 0;
}
}

/*
* Argument not found on event. But allow for comm and COMM
* to be used to get the current->comm.
*/
if (strcmp(parg->code->data, "COMM") == 0 ||
strcmp(parg->code->data, "comm") == 0) {
parg->code->op = FETCH_OP_COMM;
ret = 0;
}

kfree(parg->code->data);
parg->code->data = NULL;
return -ENOENT;
return ret;
}

static int eprobe_event_define_fields(struct trace_event_call *event_call)
Expand Down Expand Up @@ -311,6 +323,27 @@ static unsigned long get_event_field(struct fetch_insn *code, void *rec)

addr = rec + field->offset;

if (is_string_field(field)) {
switch (field->filter_type) {
case FILTER_DYN_STRING:
val = (unsigned long)(rec + (*(unsigned int *)addr & 0xffff));
break;
case FILTER_RDYN_STRING:
val = (unsigned long)(addr + (*(unsigned int *)addr & 0xffff));
break;
case FILTER_STATIC_STRING:
val = (unsigned long)addr;
break;
case FILTER_PTR_STRING:
val = (unsigned long)(*(char *)addr);
break;
default:
WARN_ON_ONCE(1);
return 0;
}
return val;
}

switch (field->size) {
case 1:
if (field->is_signed)
Expand Down Expand Up @@ -342,16 +375,38 @@ static unsigned long get_event_field(struct fetch_insn *code, void *rec)

static int get_eprobe_size(struct trace_probe *tp, void *rec)
{
struct fetch_insn *code;
struct probe_arg *arg;
int i, len, ret = 0;

for (i = 0; i < tp->nr_args; i++) {
arg = tp->args + i;
if (unlikely(arg->dynamic)) {
if (arg->dynamic) {
unsigned long val;

val = get_event_field(arg->code, rec);
len = process_fetch_insn_bottom(arg->code + 1, val, NULL, NULL);
code = arg->code;
retry:
switch (code->op) {
case FETCH_OP_TP_ARG:
val = get_event_field(code, rec);
break;
case FETCH_OP_IMM:
val = code->immediate;
break;
case FETCH_OP_COMM:
val = (unsigned long)current->comm;
break;
case FETCH_OP_DATA:
val = (unsigned long)code->data;
break;
case FETCH_NOP_SYMBOL: /* Ignore a place holder */
code++;
goto retry;
default:
continue;
}
code++;
len = process_fetch_insn_bottom(code, val, NULL, NULL);
if (len > 0)
ret += len;
}
Expand All @@ -369,8 +424,28 @@ process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
{
unsigned long val;

val = get_event_field(code, rec);
return process_fetch_insn_bottom(code + 1, val, dest, base);
retry:
switch (code->op) {
case FETCH_OP_TP_ARG:
val = get_event_field(code, rec);
break;
case FETCH_OP_IMM:
val = code->immediate;
break;
case FETCH_OP_COMM:
val = (unsigned long)current->comm;
break;
case FETCH_OP_DATA:
val = (unsigned long)code->data;
break;
case FETCH_NOP_SYMBOL: /* Ignore a place holder */
code++;
goto retry;
default:
return -EILSEQ;
}
code++;
return process_fetch_insn_bottom(code, val, dest, base);
}
NOKPROBE_SYMBOL(process_fetch_insn)

Expand Down Expand Up @@ -845,6 +920,10 @@ static int trace_eprobe_tp_update_arg(struct trace_eprobe *ep, const char *argv[
trace_probe_log_err(0, BAD_ATTACH_ARG);
}

/* Handle symbols "@" */
if (!ret)
ret = traceprobe_update_arg(&ep->tp.args[i]);

return ret;
}

Expand Down Expand Up @@ -883,7 +962,7 @@ static int __trace_eprobe_create(int argc, const char *argv[])
trace_probe_log_set_index(1);
sys_event = argv[1];
ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2, 0);
if (!sys_event || !sys_name) {
if (ret || !sys_event || !sys_name) {
trace_probe_log_err(0, NO_EVENT_INFO);
goto parse_error;
}
Expand Down
7 changes: 4 additions & 3 deletions kernel/trace/trace_event_perf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -157,7 +157,7 @@ static void perf_trace_event_unreg(struct perf_event *p_event)
int i;

if (--tp_event->perf_refcount > 0)
goto out;
return;

tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL);

Expand All @@ -176,8 +176,6 @@ static void perf_trace_event_unreg(struct perf_event *p_event)
perf_trace_buf[i] = NULL;
}
}
out:
trace_event_put_ref(tp_event);
}

static int perf_trace_event_open(struct perf_event *p_event)
Expand Down Expand Up @@ -241,6 +239,7 @@ void perf_trace_destroy(struct perf_event *p_event)
mutex_lock(&event_mutex);
perf_trace_event_close(p_event);
perf_trace_event_unreg(p_event);
trace_event_put_ref(p_event->tp_event);
mutex_unlock(&event_mutex);
}

Expand Down Expand Up @@ -292,6 +291,7 @@ void perf_kprobe_destroy(struct perf_event *p_event)
mutex_lock(&event_mutex);
perf_trace_event_close(p_event);
perf_trace_event_unreg(p_event);
trace_event_put_ref(p_event->tp_event);
mutex_unlock(&event_mutex);

destroy_local_trace_kprobe(p_event->tp_event);
Expand Down Expand Up @@ -347,6 +347,7 @@ void perf_uprobe_destroy(struct perf_event *p_event)
mutex_lock(&event_mutex);
perf_trace_event_close(p_event);
perf_trace_event_unreg(p_event);
trace_event_put_ref(p_event->tp_event);
mutex_unlock(&event_mutex);
destroy_local_trace_uprobe(p_event->tp_event);
}
Expand Down
1 change: 1 addition & 0 deletions kernel/trace/trace_events.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -176,6 +176,7 @@ static int trace_define_generic_fields(void)

__generic_field(int, CPU, FILTER_CPU);
__generic_field(int, cpu, FILTER_CPU);
__generic_field(int, common_cpu, FILTER_CPU);
__generic_field(char *, COMM, FILTER_COMM);
__generic_field(char *, comm, FILTER_COMM);

Expand Down
29 changes: 18 additions & 11 deletions kernel/trace/trace_probe.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -283,7 +283,14 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
int ret = 0;
int len;

if (strcmp(arg, "retval") == 0) {
if (flags & TPARG_FL_TPOINT) {
if (code->data)
return -EFAULT;
code->data = kstrdup(arg, GFP_KERNEL);
if (!code->data)
return -ENOMEM;
code->op = FETCH_OP_TP_ARG;
} else if (strcmp(arg, "retval") == 0) {
if (flags & TPARG_FL_RETURN) {
code->op = FETCH_OP_RETVAL;
} else {
Expand All @@ -307,7 +314,7 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
}
} else
goto inval_var;
} else if (strcmp(arg, "comm") == 0) {
} else if (strcmp(arg, "comm") == 0 || strcmp(arg, "COMM") == 0) {
code->op = FETCH_OP_COMM;
#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
} else if (((flags & TPARG_FL_MASK) ==
Expand All @@ -323,13 +330,6 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
code->op = FETCH_OP_ARG;
code->param = (unsigned int)param - 1;
#endif
} else if (flags & TPARG_FL_TPOINT) {
if (code->data)
return -EFAULT;
code->data = kstrdup(arg, GFP_KERNEL);
if (!code->data)
return -ENOMEM;
code->op = FETCH_OP_TP_ARG;
} else
goto inval_var;

Expand Down Expand Up @@ -384,6 +384,11 @@ parse_probe_arg(char *arg, const struct fetch_type *type,
break;

case '%': /* named register */
if (flags & TPARG_FL_TPOINT) {
/* eprobes do not handle registers */
trace_probe_log_err(offs, BAD_VAR);
break;
}
ret = regs_query_register_offset(arg + 1);
if (ret >= 0) {
code->op = FETCH_OP_REG;
Expand Down Expand Up @@ -617,9 +622,11 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size,

/*
* Since $comm and immediate string can not be dereferenced,
* we can find those by strcmp.
* we can find those by strcmp. But ignore for eprobes.
*/
if (strcmp(arg, "$comm") == 0 || strncmp(arg, "\\\"", 2) == 0) {
if (!(flags & TPARG_FL_TPOINT) &&
(strcmp(arg, "$comm") == 0 || strcmp(arg, "$COMM") == 0 ||
strncmp(arg, "\\\"", 2) == 0)) {
/* The type of $comm must be "string", and not an array. */
if (parg->count || (t && strcmp(t, "string")))
goto out;
Expand Down

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