trace-cmd library: Fix trace-cmd convert to handle offset update

Commit Message

Steven Rostedt April 4, 2022, 3:15 p.m. UTC

From: "Steven Rostedt (Google)" <[e-mail]>

With changing the cpu_data[]->file_offset to be unique per CPU, the
convert code had a path that was still relying on it being zero.
Specifically, when read_zpage is false. This would decompress the data
into a temp file, and the offset would be from that temp file. Thus, using
the unique file_offset would cause it to index farther than the size of
the file and crash. Instead, subtract the cpu_data[].file_offset from the
offset used in the temp file.

Fixes: add83e0c8b51 ("trace-cmd library: Fix tracecmd_read_at()")
Signed-off-by: Steven Rostedt (Google) <[e-mail]>
---
 lib/trace-cmd/trace-input.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Patch

diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index d35006294032..18bb4cf984da 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -1442,9 +1442,10 @@  static void *allocate_page_map(struct tracecmd_input *handle,
 		map_size -= map_offset + map_size -
 			(cpu_data->file_offset + cpu_data->file_size);
 
-	if (cpu_data->compress.fd >= 0)
+	if (cpu_data->compress.fd >= 0) {
+		map_offset -= cpu_data->file_offset;
 		fd = cpu_data->compress.fd;
-	else
+	} else
 		fd = handle->fd;
  again:
 	page_map->size = map_size;