[PATCH v2 0/2] trace-cmd record: Fix compression on big-endian systems

[PATCH v2 0/2] trace-cmd record: Fix compression on big-endian systems

[Ilya Leoshkevich]

v1: https://lore.kernel.org/linux-trace-devel/20250411172815.61477-1-iii@linux.ibm.com/
v1 -> v2: Factor out read_size_val(), split out the error handling
          change (Steven).

Hi,

While running trace-cmd on s390x, I ran into a few issues.
This is the fix for the first one: trace-cmd report prints nothing.

The second one is a kernel issue [1], which causes trace-cmd to print
a lot of bogus space characters.

The final one is "error in size of file '/proc/kallsyms'" caused by
delayed removal of a BPF program from /proc/kallsyms. I plan to fix it
by reading the contents of /proc/kallsyms into a temporary file before
writing it into the trace file.

[1] https://lore.kernel.org/lkml/20250411172207.61332-1-iii@linux.ibm.com/

Best regards,
Ilya

Ilya Leoshkevich (2):
  trace-cmd record: Fix compression on big-endian systems
  libtracecmd: Add missing error handling to trace-compress.c

 lib/trace-cmd/trace-compress.c | 32 +++++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

-- 
2.49.0

[PATCH v2 1/2] trace-cmd record: Fix compression on big-endian systems

[Ilya Leoshkevich]

trace-cmd report prints nothing on s390x when compression is used.

The reason is that the code treats size_t pointers as int pointers when
serializing size_t values into 32-bit on-disk fields, which works only
on little-endian systems.

Fix serialization by copying size_t values into int values first.
While at it, add overflow checks.

Fixes: 176bc1f14419 ("trace-cmd record: Fix compression when files are greater than 2GB")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 lib/trace-cmd/trace-compress.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/lib/trace-cmd/trace-compress.c b/lib/trace-cmd/trace-compress.c
index 03215ad1..e18af3dd 100644
--- a/lib/trace-cmd/trace-compress.c
+++ b/lib/trace-cmd/trace-compress.c
@@ -7,6 +7,7 @@
 #include <sys/time.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <limits.h>
 #include <unistd.h>
 
 #include "trace-cmd-private.h"
@@ -77,6 +78,16 @@ static ssize_t  write_fd(int fd, const void *data, size_t size)
 	return tot;
 }
 
+static int read_size_val(struct tep_handle *tep, size_t size, int *endian4)
+{
+	if (size > UINT_MAX)
+		return -1;
+
+	*endian4 = size;
+	*endian4 = tep_read_number(tep, endian4, 4);
+	return 0;
+}
+
 static ssize_t  do_write(struct tracecmd_compression *handle,
 			  const void *data, size_t size)
 {
@@ -331,7 +342,8 @@ int tracecmd_compress_block(struct tracecmd_compression *handle)
 		goto out;
 
 	/* Write uncompressed data size */
-	endian4 = tep_read_number(handle->tep, &handle->pointer, 4);
+	if (read_size_val(handle->tep, handle->pointer, &endian4) < 0)
+		goto out;
 	ret = do_write(handle, &endian4, 4);
 	if (ret != 4) {
 		ret = -1;
@@ -735,13 +747,15 @@ int tracecmd_compress_copy_from(struct tracecmd_compression *handle, int fd, int
 			}
 			size = ret;
 			/* Write compressed data size */
-			endian4 = tep_read_number(handle->tep, &size, 4);
+			if (read_size_val(handle->tep, size, &endian4) < 0)
+				break;
 			ret = write_fd(handle->fd, &endian4, 4);
 			if (ret != 4)
 				break;
 
 			/* Write uncompressed data size */
-			endian4 = tep_read_number(handle->tep, &all, 4);
+			if (read_size_val(handle->tep, all, &endian4) < 0)
+				break;
 			ret = write_fd(handle->fd, &endian4, 4);
 			if (ret != 4)
 				break;
@@ -763,9 +777,10 @@ int tracecmd_compress_copy_from(struct tracecmd_compression *handle, int fd, int
 	if (lseek(handle->fd, offset, SEEK_SET) == (off_t)-1)
 		return -1;
 
-	endian4 = tep_read_number(handle->tep, &chunks, 4);
+	if (read_size_val(handle->tep, chunks, &endian4) < 0)
+		return -1;
 	/* write chunks count*/
-	write_fd(handle->fd, &chunks, 4);
+	write_fd(handle->fd, &endian4, 4);
 	end_offset = lseek(handle->fd, 0, SEEK_END);
 	if (end_offset == (off_t)-1)
 		return -1;
-- 
2.49.0

[PATCH v2 2/2] libtracecmd: Add missing error handling to trace-compress.c

[Ilya Leoshkevich]

Add missing error handling to a few writes.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 lib/trace-cmd/trace-compress.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/lib/trace-cmd/trace-compress.c b/lib/trace-cmd/trace-compress.c
index e18af3dd..2a7a3e24 100644
--- a/lib/trace-cmd/trace-compress.c
+++ b/lib/trace-cmd/trace-compress.c
@@ -715,7 +715,8 @@ int tracecmd_compress_copy_from(struct tracecmd_compression *handle, int fd, int
 
 	/* save the initial offset and write 0 as initial chunk count */
 	offset = lseek(handle->fd, 0, SEEK_CUR);
-	write_fd(handle->fd, &chunks, 4);
+	if (write_fd(handle->fd, &chunks, 4) != 4)
+		return -1;
 
 	do {
 		all = 0;
@@ -780,7 +781,8 @@ int tracecmd_compress_copy_from(struct tracecmd_compression *handle, int fd, int
 	if (read_size_val(handle->tep, chunks, &endian4) < 0)
 		return -1;
 	/* write chunks count*/
-	write_fd(handle->fd, &endian4, 4);
+	if (write_fd(handle->fd, &endian4, 4) != 4)
+		return -1;
 	end_offset = lseek(handle->fd, 0, SEEK_END);
 	if (end_offset == (off_t)-1)
 		return -1;
@@ -989,7 +991,8 @@ int tracecmd_uncompress_copy_to(struct tracecmd_compression *handle, int fd,
 		if (ret < 0)
 			break;
 
-		write_fd(fd, bytes_out, ret);
+		if (write_fd(fd, bytes_out, ret) != ret)
+			break;
 		wsize += ret;
 		chunks--;
 	}
-- 
2.49.0