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

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

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KMSAN: use-after-free in n_tty_receive_buf_standard

=====================================================
BUG: KMSAN: use-after-free in variable_test_bit arch/x86/include/asm/bitops.h:227 [inline]
BUG: KMSAN: use-after-free in arch_test_bit arch/x86/include/asm/bitops.h:239 [inline]
BUG: KMSAN: use-after-free in _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
BUG: KMSAN: use-after-free in n_tty_receive_buf_standard+0xafd/0x98a0 drivers/tty/n_tty.c:1587
 variable_test_bit arch/x86/include/asm/bitops.h:227 [inline]
 arch_test_bit arch/x86/include/asm/bitops.h:239 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
 n_tty_receive_buf_standard+0xafd/0x98a0 drivers/tty/n_tty.c:1587
 __receive_buf drivers/tty/n_tty.c:1624 [inline]
 n_tty_receive_buf_common+0x198b/0x2470 drivers/tty/n_tty.c:1723
 n_tty_receive_buf2+0x4c/0x60 drivers/tty/n_tty.c:1769
 tty_ldisc_receive_buf+0xc3/0x2c0 drivers/tty/tty_buffer.c:387
 tty_port_default_receive_buf+0xd7/0x1a0 drivers/tty/tty_port.c:37
 receive_buf drivers/tty/tty_buffer.c:445 [inline]
 flush_to_ldisc+0x43e/0xe30 drivers/tty/tty_buffer.c:495
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xa2d/0x1b80 kernel/workqueue.c:3319
 worker_thread+0xedf/0x1590 kernel/workqueue.c:3400
 kthread+0xd5c/0xf00 kernel/kthread.c:463
 ret_from_fork+0x230/0x380 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was stored to memory at:
 n_tty_receive_buf_standard+0xaf6/0x98a0 arch/x86/include/asm/bitops.h:-1
 __receive_buf drivers/tty/n_tty.c:1624 [inline]
 n_tty_receive_buf_common+0x198b/0x2470 drivers/tty/n_tty.c:1723
 n_tty_receive_buf2+0x4c/0x60 drivers/tty/n_tty.c:1769
 tty_ldisc_receive_buf+0xc3/0x2c0 drivers/tty/tty_buffer.c:387
 tty_port_default_receive_buf+0xd7/0x1a0 drivers/tty/tty_port.c:37
 receive_buf drivers/tty/tty_buffer.c:445 [inline]
 flush_to_ldisc+0x43e/0xe30 drivers/tty/tty_buffer.c:495
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xa2d/0x1b80 kernel/workqueue.c:3319
 worker_thread+0xedf/0x1590 kernel/workqueue.c:3400
 kthread+0xd5c/0xf00 kernel/kthread.c:463
 ret_from_fork+0x230/0x380 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was created at:
 slab_free_hook mm/slub.c:2348 [inline]
 slab_free mm/slub.c:4695 [inline]
 kfree+0x252/0xec0 mm/slub.c:4894
 ieee80211_inform_bss+0x12f8/0x1420 net/mac80211/scan.c:160
 rdev_inform_bss net/wireless/rdev-ops.h:418 [inline]
 cfg80211_inform_single_bss_data+0x1bd1/0x3460 net/wireless/scan.c:2380
 cfg80211_inform_bss_data+0x28e/0x8c70 net/wireless/scan.c:3235
 cfg80211_inform_bss_frame_data+0x6cd/0xaa0 net/wireless/scan.c:3326
 ieee80211_bss_info_update+0x8a4/0xaa0 net/mac80211/scan.c:226
 ieee80211_scan_rx+0xa23/0xd70 net/mac80211/scan.c:355
 __ieee80211_rx_handle_packet net/mac80211/rx.c:5186 [inline]
 ieee80211_rx_list+0x464e/0x6630 net/mac80211/rx.c:5423
 ieee80211_rx_napi+0x84/0x400 net/mac80211/rx.c:5446
 ieee80211_rx include/net/mac80211.h:5210 [inline]
 ieee80211_handle_queued_frames+0x14f/0x350 net/mac80211/main.c:453
 ieee80211_tasklet_handler+0x25/0x30 net/mac80211/main.c:472
 tasklet_action_common+0x35f/0xd70 kernel/softirq.c:829
 tasklet_action+0x2d/0x40 kernel/softirq.c:855
 handle_softirqs+0x166/0x6e0 kernel/softirq.c:579
 __do_softirq kernel/softirq.c:613 [inline]
 invoke_softirq kernel/softirq.c:453 [inline]
 __irq_exit_rcu+0x66/0x180 kernel/softirq.c:680
 irq_exit_rcu+0x12/0x20 kernel/softirq.c:696
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0x84/0x90 arch/x86/kernel/apic/apic.c:1050
 asm_sysvec_apic_timer_interrupt+0x1f/0x30 arch/x86/include/asm/idtentry.h:702

CPU: 0 UID: 0 PID: 4256 Comm: kworker/u8:23 Not tainted syzkaller #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events_unbound flush_to_ldisc
=====================================================


Tested on:

commit:         bf40f4b8 Merge tag 'probes-fixes-v6.17-rc7' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14572ce2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f7564f7873be81d2
dashboard link: https://syzkaller.appspot.com/bug?extid=dd514b5f0cf048aec256
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=12499ce2580000

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

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KMSAN: use-after-free in n_tty_receive_buf_standard

=====================================================
BUG: KMSAN: use-after-free in n_tty_receive_char_special drivers/tty/n_tty.c:1347 [inline]
BUG: KMSAN: use-after-free in n_tty_receive_buf_standard+0x1283/0x98a0 drivers/tty/n_tty.c:1588
 n_tty_receive_char_special drivers/tty/n_tty.c:1347 [inline]
 n_tty_receive_buf_standard+0x1283/0x98a0 drivers/tty/n_tty.c:1588
 __receive_buf drivers/tty/n_tty.c:1624 [inline]
 n_tty_receive_buf_common+0x198b/0x2470 drivers/tty/n_tty.c:1723
 n_tty_receive_buf2+0x4c/0x60 drivers/tty/n_tty.c:1769
 tty_ldisc_receive_buf+0xc3/0x2c0 drivers/tty/tty_buffer.c:388
 tty_port_default_receive_buf+0xd7/0x1a0 drivers/tty/tty_port.c:37
 receive_buf drivers/tty/tty_buffer.c:446 [inline]
 flush_to_ldisc+0x43e/0xe30 drivers/tty/tty_buffer.c:496
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xa2d/0x1b80 kernel/workqueue.c:3319
 worker_thread+0xedf/0x1590 kernel/workqueue.c:3400
 kthread+0xd5c/0xf00 kernel/kthread.c:463
 ret_from_fork+0x230/0x380 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was created at:
 slab_free_hook mm/slub.c:2348 [inline]
 slab_free mm/slub.c:4695 [inline]
 kfree+0x252/0xec0 mm/slub.c:4894
 ieee80211_ibss_rx_queued_mgmt+0x2eea/0x3e80 net/mac80211/ibss.c:-1
 ieee80211_iface_process_skb net/mac80211/iface.c:1699 [inline]
 ieee80211_iface_work+0x11c7/0x1e70 net/mac80211/iface.c:1753
 cfg80211_wiphy_work+0x341/0x850 net/wireless/core.c:435
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xa2d/0x1b80 kernel/workqueue.c:3319
 worker_thread+0xedf/0x1590 kernel/workqueue.c:3400
 kthread+0xd5c/0xf00 kernel/kthread.c:463
 ret_from_fork+0x230/0x380 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

CPU: 0 UID: 0 PID: 3884 Comm: kworker/u8:21 Not tainted syzkaller #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events_unbound flush_to_ldisc
=====================================================


Tested on:

commit:         bf40f4b8 Merge tag 'probes-fixes-v6.17-rc7' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17a134e2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f7564f7873be81d2
dashboard link: https://syzkaller.appspot.com/bug?extid=dd514b5f0cf048aec256
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=173a34e2580000

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

[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+dd514b5f0cf048aec256@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.

[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+dd514b5f0cf048aec256@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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