linux-kernel - [syzbot] [net?] [input?] [usb?] memory leak in ldisc

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Message-ID: <696bc81f.050a0220.3390f1.000f.GAE@google.com>
Date: Sat, 17 Jan 2026 09:34:23 -0800
From: syzbot <syzbot+f9d847b2b84164fa69f3@...kaller.appspotmail.com>
To: andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com, 
	kuba@...nel.org, linux-input@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-usb@...r.kernel.org, netdev@...r.kernel.org, pabeni@...hat.com, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [net?] [input?] [usb?] memory leak in ldisc_receive

Hello,

syzbot found the following issue on:

HEAD commit:    b71e635feefc Merge tag 'cgroup-for-6.19-rc5-fixes' of git:..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1638a59a580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=87bc41cae23d2144
dashboard link: https://syzkaller.appspot.com/bug?extid=f9d847b2b84164fa69f3
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=162985fc580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1035f922580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/821cfcb36509/disk-b71e635f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/80f2b6f81538/vmlinux-b71e635f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c5a9299bca98/bzImage-b71e635f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f9d847b2b84164fa69f3@...kaller.appspotmail.com

BUG: memory leak
unreferenced object 0xffff888109d88b00 (size 240):
  comm "syz.0.17", pid 6088, jiffies 4294942822
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 20 8e 13 81 88 ff ff 00 00 00 00 00 00 00 00  . ..............
  backtrace (crc cd2b8445):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4958 [inline]
    slab_alloc_node mm/slub.c:5263 [inline]
    kmem_cache_alloc_node_noprof+0x384/0x5a0 mm/slub.c:5315
    __alloc_skb+0xe8/0x2b0 net/core/skbuff.c:679
    __netdev_alloc_skb+0x72/0x230 net/core/skbuff.c:754
    netdev_alloc_skb include/linux/skbuff.h:3484 [inline]
    ldisc_receive+0x7d/0x210 drivers/net/caif/caif_serial.c:176
    tiocsti drivers/tty/tty_io.c:2290 [inline]
    tty_ioctl+0x329/0xd40 drivers/tty/tty_io.c:2706
    vfs_ioctl fs/ioctl.c:51 [inline]
    __do_sys_ioctl fs/ioctl.c:597 [inline]
    __se_sys_ioctl fs/ioctl.c:583 [inline]
    __x64_sys_ioctl+0xf4/0x140 fs/ioctl.c:583
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff88810a368500 (size 240):
  comm "syz.0.18", pid 6193, jiffies 4294942941
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 20 94 13 81 88 ff ff 00 00 00 00 00 00 00 00  . ..............
  backtrace (crc 5d1300cb):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4958 [inline]
    slab_alloc_node mm/slub.c:5263 [inline]
    kmem_cache_alloc_node_noprof+0x384/0x5a0 mm/slub.c:5315
    __alloc_skb+0xe8/0x2b0 net/core/skbuff.c:679
    __netdev_alloc_skb+0x72/0x230 net/core/skbuff.c:754
    netdev_alloc_skb include/linux/skbuff.h:3484 [inline]
    ldisc_receive+0x7d/0x210 drivers/net/caif/caif_serial.c:176
    tiocsti drivers/tty/tty_io.c:2290 [inline]
    tty_ioctl+0x329/0xd40 drivers/tty/tty_io.c:2706
    vfs_ioctl fs/ioctl.c:51 [inline]
    __do_sys_ioctl fs/ioctl.c:597 [inline]
    __se_sys_ioctl fs/ioctl.c:583 [inline]
    __x64_sys_ioctl+0xf4/0x140 fs/ioctl.c:583
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff88810a9e2c00 (size 704):
  comm "syz.0.18", pid 6193, jiffies 4294942941
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc b6200c):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4958 [inline]
    slab_alloc_node mm/slub.c:5263 [inline]
    kmem_cache_alloc_node_noprof+0x384/0x5a0 mm/slub.c:5315
    kmalloc_reserve+0xe6/0x180 net/core/skbuff.c:586
    __alloc_skb+0x111/0x2b0 net/core/skbuff.c:690
    __netdev_alloc_skb+0x72/0x230 net/core/skbuff.c:754
    netdev_alloc_skb include/linux/skbuff.h:3484 [inline]
    ldisc_receive+0x7d/0x210 drivers/net/caif/caif_serial.c:176
    tiocsti drivers/tty/tty_io.c:2290 [inline]
    tty_ioctl+0x329/0xd40 drivers/tty/tty_io.c:2706
    vfs_ioctl fs/ioctl.c:51 [inline]
    __do_sys_ioctl fs/ioctl.c:597 [inline]
    __se_sys_ioctl fs/ioctl.c:583 [inline]
    __x64_sys_ioctl+0xf4/0x140 fs/ioctl.c:583
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff888109ddda00 (size 240):
  comm "syz.0.19", pid 6262, jiffies 4294943059
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 50 8e 13 81 88 ff ff 00 00 00 00 00 00 00 00  .P..............
  backtrace (crc 3f6ba7c1):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4958 [inline]
    slab_alloc_node mm/slub.c:5263 [inline]
    kmem_cache_alloc_node_noprof+0x384/0x5a0 mm/slub.c:5315
    __alloc_skb+0xe8/0x2b0 net/core/skbuff.c:679
    __netdev_alloc_skb+0x72/0x230 net/core/skbuff.c:754
    netdev_alloc_skb include/linux/skbuff.h:3484 [inline]
    ldisc_receive+0x7d/0x210 drivers/net/caif/caif_serial.c:176
    tiocsti drivers/tty/tty_io.c:2290 [inline]
    tty_ioctl+0x329/0xd40 drivers/tty/tty_io.c:2706
    vfs_ioctl fs/ioctl.c:51 [inline]
    __do_sys_ioctl fs/ioctl.c:597 [inline]
    __se_sys_ioctl fs/ioctl.c:583 [inline]
    __x64_sys_ioctl+0xf4/0x140 fs/ioctl.c:583
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

connection error: failed to recv *flatrpc.ExecutorMessageRawT: EOF


---
This report is generated by a bot. It may contain errors.
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