[PATCH v1 4/8] perf header: Fail read if header sections overlap

[Ian Rogers <irogers@google.com>]

Buggy perf.data files can have the attributes and data
overlapping. For example, when processing pipe data the attributes
aren't known and so file offset header calculations can consider them
not present.  Later this can cause the attributes to overwrite the
data. This can be seen in:

```
$ perf record -o - true > a.data
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.059 MB - ]
$ perf inject -i a.data -o b.data
$ perf report --stats -i b.data
0x68 [0]: failed to process type: 510379 [Invalid argument]
Error:
failed to process sample
```

This change makes reading the corrupt file fail:

```
$ perf report --stats -i b.data
Perf file header corrupt: Attributes and data overlap
incompatible file format (rerun with -v to learn more)
```

Which is more informative.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/header.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 3309fe7f1d12..65c9086610cb 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -3986,6 +3986,24 @@ int perf_file_header__read(struct perf_file_header *header,
 			     adds_features));
 	}
 
+	if (header->size > header->attrs.offset) {
+		pr_err("Perf file header corrupt: header overlaps attrs\n");
+		return -1;
+	}
+
+	if (header->size > header->data.offset) {
+		pr_err("Perf file header corrupt: header overlaps data\n");
+		return -1;
+	}
+
+	if ((header->attrs.offset <= header->data.offset &&
+	     header->attrs.offset + header->attrs.size > header->data.offset) ||
+	    (header->attrs.offset > header->data.offset &&
+	     header->data.offset + header->data.size > header->attrs.offset)) {
+		pr_err("Perf file header corrupt: Attributes and data overlap\n");
+		return -1;
+	}
+
 	if (header->size != sizeof(*header)) {
 		/* Support the previous format */
 		if (header->size == offsetof(typeof(*header), adds_features))
-- 
2.46.0.295.g3b9ea8a38a-goog