From: Masami Hiramatsu <mhiramat(a)kernel.org>
Since the string type can not be the target of the addition / subtraction
operation, it must be rejected. Without this fix, the string type silently
converted to digits.
Link: https://lkml.kernel.org/r/162742654278.290973.1523000673366456634.stgit@dev…
Cc: stable(a)vger.kernel.org
Fixes: 100719dcef447 ("tracing: Add simple expression support to hist triggers")
Signed-off-by: Masami Hiramatsu <mhiramat(a)kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt(a)goodmis.org>
---
kernel/trace/trace_events_hist.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 362db9b81b8d..949ef09dc537 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -65,7 +65,8 @@
C(INVALID_SORT_MODIFIER,"Invalid sort modifier"), \
C(EMPTY_SORT_FIELD, "Empty sort field"), \
C(TOO_MANY_SORT_FIELDS, "Too many sort fields (Max = 2)"), \
- C(INVALID_SORT_FIELD, "Sort field must be a key or a val"),
+ C(INVALID_SORT_FIELD, "Sort field must be a key or a val"), \
+ C(INVALID_STR_OPERAND, "String type can not be an operand in expression"),
#undef C
#define C(a, b) HIST_ERR_##a
@@ -2156,6 +2157,13 @@ static struct hist_field *parse_unary(struct hist_trigger_data *hist_data,
ret = PTR_ERR(operand1);
goto free;
}
+ if (operand1->flags & HIST_FIELD_FL_STRING) {
+ /* String type can not be the operand of unary operator. */
+ hist_err(file->tr, HIST_ERR_INVALID_STR_OPERAND, errpos(str));
+ destroy_hist_field(operand1, 0);
+ ret = -EINVAL;
+ goto free;
+ }
expr->flags |= operand1->flags &
(HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);
@@ -2257,6 +2265,11 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
operand1 = NULL;
goto free;
}
+ if (operand1->flags & HIST_FIELD_FL_STRING) {
+ hist_err(file->tr, HIST_ERR_INVALID_STR_OPERAND, errpos(operand1_str));
+ ret = -EINVAL;
+ goto free;
+ }
/* rest of string could be another expression e.g. b+c in a+b+c */
operand_flags = 0;
@@ -2266,6 +2279,11 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
operand2 = NULL;
goto free;
}
+ if (operand2->flags & HIST_FIELD_FL_STRING) {
+ hist_err(file->tr, HIST_ERR_INVALID_STR_OPERAND, errpos(str));
+ ret = -EINVAL;
+ goto free;
+ }
ret = check_expr_operands(file->tr, operand1, operand2);
if (ret)
--
2.30.2
From: "Steven Rostedt (VMware)" <rostedt(a)goodmis.org>
When working on my user space applications, I found a bug in the synthetic
event code where the automated synthetic event field was not matching the
event field calculation it was attached to. Looking deeper into it, it was
because the calculation hist_field was not given a size.
The synthetic event fields are matched to their hist_fields either by
having the field have an identical string type, or if that does not match,
then the size and signed values are used to match the fields.
The problem arose when I tried to match a calculation where the fields
were "unsigned int". My tool created a synthetic event of type "u32". But
it failed to match. The string was:
diff=field1-field2:onmatch(event).trace(synth,$diff)
Adding debugging into the kernel, I found that the size of "diff" was 0.
And since it was given "unsigned int" as a type, the histogram fallback
code used size and signed. The signed matched, but the size of u32 (4) did
not match zero, and the event failed to be created.
This can be worse if the field you want to match is not one of the
acceptable fields for a synthetic event. As event fields can have any type
that is supported in Linux, this can cause an issue. For example, if a
type is an enum. Then there's no way to use that with any calculations.
Have the calculation field simply take on the size of what it is
calculating.
Link: https://lkml.kernel.org/r/20210730171951.59c7743f@oasis.local.home
Cc: Tom Zanussi <zanussi(a)kernel.org>
Cc: Masami Hiramatsu <mhiramat(a)kernel.org>
Cc: Namhyung Kim <namhyung(a)kernel.org>
Cc: Ingo Molnar <mingo(a)kernel.org>
Cc: Andrew Morton <akpm(a)linux-foundation.org>
Cc: stable(a)vger.kernel.org
Fixes: 100719dcef447 ("tracing: Add simple expression support to hist triggers")
Signed-off-by: Steven Rostedt (VMware) <rostedt(a)goodmis.org>
---
kernel/trace/trace_events_hist.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 34325f41ebc0..362db9b81b8d 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -2287,6 +2287,10 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
expr->operands[0] = operand1;
expr->operands[1] = operand2;
+
+ /* The operand sizes should be the same, so just pick one */
+ expr->size = operand1->size;
+
expr->operator = field_op;
expr->name = expr_str(expr, 0);
expr->type = kstrdup(operand1->type, GFP_KERNEL);
--
2.30.2