[syzbot] [serial?] KMSAN: uninit-value in n_tty_receive_buf_closing (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1fb918967b56 Merge tag 'for-6.11-rc3-tag' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10383409980000
kernel config: https://syzkaller.appspot.com/x/.config?x=836be0e882e376f7
dashboard link: https://syzkaller.appspot.com/bug?extid=dd514b5f0cf048aec256
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c4ce70611394/disk-1fb91896.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/014bed8fa88a/vmlinux-1fb91896.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f8aa322233dc/bzImage-1fb91896.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dd514b...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in n_tty_receive_char_closing drivers/tty/n_tty.c:1454 [inline]
BUG: KMSAN: uninit-value in n_tty_receive_buf_closing+0x539/0xb40 drivers/tty/n_tty.c:1567
n_tty_receive_char_closing drivers/tty/n_tty.c:1454 [inline]
n_tty_receive_buf_closing+0x539/0xb40 drivers/tty/n_tty.c:1567
__receive_buf drivers/tty/n_tty.c:1630 [inline]
n_tty_receive_buf_common+0x196b/0x2490 drivers/tty/n_tty.c:1739
n_tty_receive_buf2+0x4c/0x60 drivers/tty/n_tty.c:1785
tty_ldisc_receive_buf+0xd0/0x290 drivers/tty/tty_buffer.c:387
tty_port_default_receive_buf+0xdf/0x190 drivers/tty/tty_port.c:37
receive_buf drivers/tty/tty_buffer.c:445 [inline]
flush_to_ldisc+0x473/0xdb0 drivers/tty/tty_buffer.c:495
process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3312
worker_thread+0xea5/0x1520 kernel/workqueue.c:3390
kthread+0x3dd/0x540 kernel/kthread.c:389
ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was created at:
slab_post_alloc_hook mm/slub.c:3994 [inline]
slab_alloc_node mm/slub.c:4037 [inline]
__do_kmalloc_node mm/slub.c:4157 [inline]
__kmalloc_noprof+0x661/0xf30 mm/slub.c:4170
kmalloc_noprof include/linux/slab.h:685 [inline]
tty_buffer_alloc drivers/tty/tty_buffer.c:180 [inline]
__tty_buffer_request_room+0x36e/0x6d0 drivers/tty/tty_buffer.c:273
__tty_insert_flip_string_flags+0x140/0x570 drivers/tty/tty_buffer.c:309
tty_insert_flip_char include/linux/tty_flip.h:77 [inline]
uart_insert_char+0x39e/0xa10 drivers/tty/serial/serial_core.c:3568
serial8250_read_char+0x1a7/0x5d0 drivers/tty/serial/8250/8250_port.c:1743
serial8250_rx_chars drivers/tty/serial/8250/8250_port.c:1760 [inline]
serial8250_handle_irq+0x77a/0xb80 drivers/tty/serial/8250/8250_port.c:1924
serial8250_default_handle_irq+0x120/0x2b0 drivers/tty/serial/8250/8250_port.c:1949
serial8250_interrupt+0xc5/0x360 drivers/tty/serial/8250/8250_core.c:86
__handle_irq_event_percpu+0x118/0xca0 kernel/irq/handle.c:158
handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
handle_irq_event+0xef/0x2c0 kernel/irq/handle.c:210
handle_edge_irq+0x340/0xfb0 kernel/irq/chip.c:831
generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
handle_irq arch/x86/kernel/irq.c:247 [inline]
call_irq_handler arch/x86/kernel/irq.c:259 [inline]
__common_interrupt+0x97/0x1f0 arch/x86/kernel/irq.c:285
common_interrupt+0x8f/0xa0 arch/x86/kernel/irq.c:278
asm_common_interrupt+0x2b/0x40 arch/x86/include/asm/idtentry.h:693

CPU: 1 UID: 0 PID: 3148 Comm: kworker/u8:16 Not tainted 6.11.0-rc3-syzkaller-00066-g1fb918967b56 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
Workqueue: events_unbound flush_to_ldisc
=====================================================


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: d6ef8b40d075 Merge tag 'sound-6.13-rc5' of git://git.kerne..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=106692c4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f9048090d7bb0d06

dashboard link: https://syzkaller.appspot.com/bug?extid=dd514b5f0cf048aec256
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1741d018580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16b87adf980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/956144bfc94b/disk-d6ef8b40.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fdff012f5017/vmlinux-d6ef8b40.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c97fa2a32556/bzImage-d6ef8b40.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dd514b...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in n_tty_receive_char_closing drivers/tty/n_tty.c:1454 [inline]
BUG: KMSAN: uninit-value in n_tty_receive_buf_closing+0x539/0xb40 drivers/tty/n_tty.c:1567
n_tty_receive_char_closing drivers/tty/n_tty.c:1454 [inline]
n_tty_receive_buf_closing+0x539/0xb40 drivers/tty/n_tty.c:1567
__receive_buf drivers/tty/n_tty.c:1630 [inline]
n_tty_receive_buf_common+0x196b/0x2490 drivers/tty/n_tty.c:1739
n_tty_receive_buf2+0x4c/0x60 drivers/tty/n_tty.c:1785
tty_ldisc_receive_buf+0xd0/0x290 drivers/tty/tty_buffer.c:387
tty_port_default_receive_buf+0xdf/0x190 drivers/tty/tty_port.c:37
receive_buf drivers/tty/tty_buffer.c:445 [inline]
flush_to_ldisc+0x473/0xdb0 drivers/tty/tty_buffer.c:495

process_one_work kernel/workqueue.c:3229 [inline]
process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3310
worker_thread+0xea7/0x14f0 kernel/workqueue.c:3391
kthread+0x3e2/0x540 kernel/kthread.c:389

ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was created at:

slab_post_alloc_hook mm/slub.c:4125 [inline]
slab_alloc_node mm/slub.c:4168 [inline]
__do_kmalloc_node mm/slub.c:4297 [inline]
__kmalloc_noprof+0x923/0x1230 mm/slub.c:4310
kmalloc_noprof include/linux/slab.h:905 [inline]

tty_buffer_alloc drivers/tty/tty_buffer.c:180 [inline]
__tty_buffer_request_room+0x36e/0x6d0 drivers/tty/tty_buffer.c:273
__tty_insert_flip_string_flags+0x140/0x570 drivers/tty/tty_buffer.c:309
tty_insert_flip_char include/linux/tty_flip.h:77 [inline]

uart_insert_char+0x39e/0xa10 drivers/tty/serial/serial_core.c:3550
serial8250_read_char+0x1a7/0x5d0 drivers/tty/serial/8250/8250_port.c:1763
serial8250_rx_chars drivers/tty/serial/8250/8250_port.c:1780 [inline]
serial8250_handle_irq+0x970/0x1130 drivers/tty/serial/8250/8250_port.c:1944
serial8250_default_handle_irq+0x120/0x2b0 drivers/tty/serial/8250/8250_port.c:1969

serial8250_interrupt+0xc5/0x360 drivers/tty/serial/8250/8250_core.c:86
__handle_irq_event_percpu+0x118/0xca0 kernel/irq/handle.c:158
handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
handle_irq_event+0xef/0x2c0 kernel/irq/handle.c:210
handle_edge_irq+0x340/0xfb0 kernel/irq/chip.c:831
generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
handle_irq arch/x86/kernel/irq.c:247 [inline]
call_irq_handler arch/x86/kernel/irq.c:259 [inline]
__common_interrupt+0x97/0x1f0 arch/x86/kernel/irq.c:285

common_interrupt+0x92/0xb0 arch/x86/kernel/irq.c:278
asm_common_interrupt+0x2b/0x40 arch/x86/include/asm/idtentry.h:693

CPU: 1 UID: 0 PID: 59 Comm: kworker/u8:3 Not tainted 6.13.0-rc4-syzkaller-00054-gd6ef8b40d075 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024

Workqueue: events_unbound flush_to_ldisc
=====================================================


---

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

[s gavini]

#sys test https://github.com/sumanth-gavini/linux.git

[Pei Xiao]

#syz test
---
drivers/tty/tty_buffer.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 67271fc0b223..62d32556a24b 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -108,6 +108,7 @@ static void tty_buffer_reset(struct tty_buffer *p, size_t size)
p->lookahead = 0;
p->read = 0;
p->flags = true;
+ memset(p->data, 0, size);
}

/**
@@ -177,7 +178,7 @@ static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size)
*/
if (atomic_read(&port->buf.mem_used) > port->buf.mem_limit)
return NULL;
- p = kmalloc(struct_size(p, data, 2 * size), GFP_ATOMIC | __GFP_NOWARN);
+ p = kzalloc(struct_size(p, data, 2 * size), GFP_ATOMIC | __GFP_NOWARN);
if (p == NULL)
return NULL;

--
2.25.1

[Pei Xiao]