Re: [syzbot] [media?] KMSAN: uninit-value in vidtv_ts_null_write_into

[Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>]

On Sun, 15 Feb 2026 02:49:27 -0800, Syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    cd7a5651db26 alpha: add missing address argument in call t..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=125b62aa580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=50148b563a4d5941
> dashboard link: https://syzkaller.appspot.com/bug?extid=96f901260a0b2d29cd1a
> compiler:       Debian clang version 21.1.8
> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD >
> 21.1.8
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13e5a6e6580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=172c7e5a580000
> 

#syz test

Signed-off-by: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
---
 drivers/media/test-drivers/vidtv/vidtv_mux.c |  4 +-
 drivers/media/test-drivers/vidtv/vidtv_ts.c  | 48 ++++++++++----------
 drivers/media/test-drivers/vidtv/vidtv_ts.h  |  4 +-
 3 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/drivers/media/test-drivers/vidtv/vidtv_mux.c b/drivers/media/test-drivers/vidtv/vidtv_mux.c
index f99878eff7ac..7dad97881fdb 100644
--- a/drivers/media/test-drivers/vidtv/vidtv_mux.c
+++ b/drivers/media/test-drivers/vidtv/vidtv_mux.c
@@ -233,7 +233,7 @@ static u32 vidtv_mux_push_pcr(struct vidtv_mux *m)
 	/* the 27Mhz clock will feed both parts of the PCR bitfield */
 	args.pcr = m->timing.clk;

-	nbytes += vidtv_ts_pcr_write_into(args);
+	nbytes += vidtv_ts_pcr_write_into(&args);
 	m->mux_buf_offset += nbytes;

 	m->num_streamed_pcr++;
@@ -363,7 +363,7 @@ static u32 vidtv_mux_pad_with_nulls(struct vidtv_mux *m, u32 npkts)
 	args.continuity_counter = &ctx->cc;

 	for (i = 0; i < npkts; ++i) {
-		m->mux_buf_offset += vidtv_ts_null_write_into(args);
+		m->mux_buf_offset += vidtv_ts_null_write_into(&args);
 		args.dest_offset  = m->mux_buf_offset;
 	}

diff --git a/drivers/media/test-drivers/vidtv/vidtv_ts.c b/drivers/media/test-drivers/vidtv/vidtv_ts.c
index ca4bb9c40b78..cbe9aff9ffb5 100644
--- a/drivers/media/test-drivers/vidtv/vidtv_ts.c
+++ b/drivers/media/test-drivers/vidtv/vidtv_ts.c
@@ -48,7 +48,7 @@ void vidtv_ts_inc_cc(u8 *continuity_counter)
 		*continuity_counter = 0;
 }

-u32 vidtv_ts_null_write_into(struct null_packet_write_args args)
+u32 vidtv_ts_null_write_into(const struct null_packet_write_args *args)
 {
 	u32 nbytes = 0;
 	struct vidtv_mpeg_ts ts_header = {};
@@ -56,21 +56,21 @@ u32 vidtv_ts_null_write_into(struct null_packet_write_args args)
 	ts_header.sync_byte          = TS_SYNC_BYTE;
 	ts_header.bitfield           = cpu_to_be16(TS_NULL_PACKET_PID);
 	ts_header.payload            = 1;
-	ts_header.continuity_counter = *args.continuity_counter;
+	ts_header.continuity_counter = *args->continuity_counter;

 	/* copy TS header */
-	nbytes += vidtv_memcpy(args.dest_buf,
-			       args.dest_offset + nbytes,
-			       args.buf_sz,
+	nbytes += vidtv_memcpy(args->dest_buf,
+			       args->dest_offset + nbytes,
+			       args->buf_sz,
 			       &ts_header,
 			       sizeof(ts_header));

-	vidtv_ts_inc_cc(args.continuity_counter);
+	vidtv_ts_inc_cc(args->continuity_counter);

 	/* fill the rest with empty data */
-	nbytes += vidtv_memset(args.dest_buf,
-			       args.dest_offset + nbytes,
-			       args.buf_sz,
+	nbytes += vidtv_memset(args->dest_buf,
+			       args->dest_offset + nbytes,
+			       args->buf_sz,
 			       TS_FILL_BYTE,
 			       TS_PACKET_LEN - nbytes);

@@ -83,17 +83,17 @@ u32 vidtv_ts_null_write_into(struct null_packet_write_args args)
 	return nbytes;
 }

-u32 vidtv_ts_pcr_write_into(struct pcr_write_args args)
+u32 vidtv_ts_pcr_write_into(const struct pcr_write_args *args)
 {
 	u32 nbytes = 0;
 	struct vidtv_mpeg_ts ts_header = {};
 	struct vidtv_mpeg_ts_adaption ts_adap = {};

 	ts_header.sync_byte     = TS_SYNC_BYTE;
-	ts_header.bitfield      = cpu_to_be16(args.pid);
+	ts_header.bitfield      = cpu_to_be16(args->pid);
 	ts_header.scrambling    = 0;
 	/* cc is not incremented, but it is needed. see 13818-1 clause 2.4.3.3 */
-	ts_header.continuity_counter = *args.continuity_counter;
+	ts_header.continuity_counter = *args->continuity_counter;
 	ts_header.payload            = 0;
 	ts_header.adaptation_field   = 1;

@@ -102,27 +102,27 @@ u32 vidtv_ts_pcr_write_into(struct pcr_write_args args)
 	ts_adap.PCR    = 1;

 	/* copy TS header */
-	nbytes += vidtv_memcpy(args.dest_buf,
-			       args.dest_offset + nbytes,
-			       args.buf_sz,
+	nbytes += vidtv_memcpy(args->dest_buf,
+			       args->dest_offset + nbytes,
+			       args->buf_sz,
 			       &ts_header,
 			       sizeof(ts_header));

 	/* write the adap after the TS header */
-	nbytes += vidtv_memcpy(args.dest_buf,
-			       args.dest_offset + nbytes,
-			       args.buf_sz,
+	nbytes += vidtv_memcpy(args->dest_buf,
+			       args->dest_offset + nbytes,
+			       args->buf_sz,
 			       &ts_adap,
 			       sizeof(ts_adap));

 	/* write the PCR optional */
-	nbytes += vidtv_ts_write_pcr_bits(args.dest_buf,
-					  args.dest_offset + nbytes,
-					  args.pcr);
+	nbytes += vidtv_ts_write_pcr_bits(args->dest_buf,
+					  args->dest_offset + nbytes,
+					  args->pcr);

-	nbytes += vidtv_memset(args.dest_buf,
-			       args.dest_offset + nbytes,
-			       args.buf_sz,
+	nbytes += vidtv_memset(args->dest_buf,
+			       args->dest_offset + nbytes,
+			       args->buf_sz,
 			       TS_FILL_BYTE,
 			       TS_PACKET_LEN - nbytes);

diff --git a/drivers/media/test-drivers/vidtv/vidtv_ts.h b/drivers/media/test-drivers/vidtv/vidtv_ts.h
index 09b4ffd02829..3606398e160d 100644
--- a/drivers/media/test-drivers/vidtv/vidtv_ts.h
+++ b/drivers/media/test-drivers/vidtv/vidtv_ts.h
@@ -90,7 +90,7 @@ void vidtv_ts_inc_cc(u8 *continuity_counter);
  *
  * Return: The number of bytes written into the buffer.
  */
-u32 vidtv_ts_null_write_into(struct null_packet_write_args args);
+u32 vidtv_ts_null_write_into(const struct null_packet_write_args *args);

 /**
  * vidtv_ts_pcr_write_into - Write a PCR  packet into a buffer.
@@ -101,6 +101,6 @@ u32 vidtv_ts_null_write_into(struct null_packet_write_args args);
  *
  * Return: The number of bytes written into the buffer.
  */
-u32 vidtv_ts_pcr_write_into(struct pcr_write_args args);
+u32 vidtv_ts_pcr_write_into(const struct pcr_write_args *args);

 #endif //VIDTV_TS_H
--

-- 
Best Regards,
Abd-Alrhman