On 7/29/2021 7:44 PM, Marcel Holtmann wrote:
Hi Phi,
Hello,
syzbot found the following crash on:
HEAD commit: abf02e29 Merge tag 'pm-5.2-rc6' of
git://git.kernel.org/pu <http://git.kernel.org/pu>..
git tree: upstream
console output:
https://syzkaller.appspot.com/x/log.txt?x=1054e6b2a00000
<https://syzkaller.appspot.com/x/log.txt?x=1054e6b2a00000>
kernel config:
https://syzkaller.appspot.com/x/.config?x=56f1da14935c3cce
<https://syzkaller.appspot.com/x/.config?x=56f1da14935c3cce>
dashboard link:
https://syzkaller.appspot.com/bug?extid=97388eb9d31b997fe1d0
<https://syzkaller.appspot.com/bug?extid=97388eb9d31b997fe1d0>
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:
https://syzkaller.appspot.com/x/repro.syz?x=1073d8aaa00000
<https://syzkaller.appspot.com/x/repro.syz?x=1073d8aaa00000>
C reproducer:
https://syzkaller.appspot.com/x/repro.c?x=17b36fbea00000
<https://syzkaller.appspot.com/x/repro.c?x=17b36fbea00000>
IMPORTANT: if you fix the bug, please add the following tag to the
commit:
Reported-by: syzbot+97388e...@xxxxxxxxxxxxxxxxxxxxxxxxx
program
BUG: memory leak
unreferenced object 0xffff88810991fa00 (size 224):
comm "syz-executor739", pid 7080, jiffies 4294949854 (age 18.640s)
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:
[<00000000da42c09f>] kmemleak_alloc_recursive
include/linux/kmemleak.h:43 [inline]
[<00000000da42c09f>] slab_post_alloc_hook mm/slab.h:439 [inline]
[<00000000da42c09f>] slab_alloc_node mm/slab.c:3269 [inline]
[<00000000da42c09f>] kmem_cache_alloc_node+0x153/0x2a0 mm/slab.c:3579
[<00000000f6fbcf84>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:194
[<00000000ea93fc4c>] alloc_skb include/linux/skbuff.h:1054 [inline]
[<00000000ea93fc4c>] bt_skb_alloc include/net/bluetooth/bluetooth.h:339
[inline]
[<00000000ea93fc4c>] h4_recv_buf+0x26d/0x450
drivers/bluetooth/hci_h4.c:182
[<00000000e0312475>] h4_recv+0x51/0xb0 drivers/bluetooth/hci_h4.c:116
[<00000000ebf11fab>] hci_uart_tty_receive+0xba/0x200
drivers/bluetooth/hci_ldisc.c:592
[<0000000095e1216e>] tiocsti drivers/tty/tty_io.c:2195 [inline]
[<0000000095e1216e>] tty_ioctl+0x81c/0xa30 drivers/tty/tty_io.c:2571
[<000000009fa523f0>] vfs_ioctl fs/ioctl.c:46 [inline]
[<000000009fa523f0>] file_ioctl fs/ioctl.c:509 [inline]
[<000000009fa523f0>] do_vfs_ioctl+0x62a/0x810 fs/ioctl.c:696
[<000000000cebb5d9>] ksys_ioctl+0x86/0xb0 fs/ioctl.c:713
[<000000001630008a>] __do_sys_ioctl fs/ioctl.c:720 [inline]
[<000000001630008a>] __se_sys_ioctl fs/ioctl.c:718 [inline]
[<000000001630008a>] __x64_sys_ioctl+0x1e/0x30 fs/ioctl.c:718
[<00000000c62091e3>] do_syscall_64+0x76/0x1a0
arch/x86/entry/common.c:301
[<000000005c213625>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
BUG: memory leak
unreferenced object 0xffff8881204f4400 (size 1024):
comm "syz-executor739", pid 7080, jiffies 4294949854 (age 18.640s)
hex dump (first 32 bytes):
6c 69 62 75 64 65 76 00 fe ed ca fe 28 00 00 00 libudev.....(...
28 00 00 00 a0 00 00 00 52 ca da 77 00 00 00 00 (.......R..w....
backtrace:
[<0000000034504843>] kmemleak_alloc_recursive
include/linux/kmemleak.h:43 [inline]
[<0000000034504843>] slab_post_alloc_hook mm/slab.h:439 [inline]
[<0000000034504843>] slab_alloc_node mm/slab.c:3269 [inline]
[<0000000034504843>] kmem_cache_alloc_node_trace+0x15b/0x2a0
mm/slab.c:3597
[<0000000056d30eb5>] __do_kmalloc_node mm/slab.c:3619 [inline]
[<0000000056d30eb5>] __kmalloc_node_track_caller+0x38/0x50
mm/slab.c:3634
[<00000000df40176c>] __kmalloc_reserve.isra.0+0x40/0xb0
net/core/skbuff.c:138
[<0000000035340e64>] __alloc_skb+0xa0/0x210 net/core/skbuff.c:206
[<00000000ea93fc4c>] alloc_skb include/linux/skbuff.h:1054 [inline]
[<00000000ea93fc4c>] bt_skb_alloc include/net/bluetooth/bluetooth.h:339
[inline]
[<00000000ea93fc4c>] h4_recv_buf+0x26d/0x450
drivers/bluetooth/hci_h4.c:182
[<00000000e0312475>] h4_recv+0x51/0xb0 drivers/bluetooth/hci_h4.c:116
[<00000000ebf11fab>] hci_uart_tty_receive+0xba/0x200
drivers/bluetooth/hci_ldisc.c:592
[<0000000095e1216e>] tiocsti drivers/tty/tty_io.c:2195 [inline]
[<0000000095e1216e>] tty_ioctl+0x81c/0xa30 drivers/tty/tty_io.c:2571
[<000000009fa523f0>] vfs_ioctl fs/ioctl.c:46 [inline]
[<000000009fa523f0>] file_ioctl fs/ioctl.c:509 [inline]
[<000000009fa523f0>] do_vfs_ioctl+0x62a/0x810 fs/ioctl.c:696
[<000000000cebb5d9>] ksys_ioctl+0x86/0xb0 fs/ioctl.c:713
[<000000001630008a>] __do_sys_ioctl fs/ioctl.c:720 [inline]
[<000000001630008a>] __se_sys_ioctl fs/ioctl.c:718 [inline]
[<000000001630008a>] __x64_sys_ioctl+0x1e/0x30 fs/ioctl.c:718
[<00000000c62091e3>] do_syscall_64+0x76/0x1a0
arch/x86/entry/common.c:301
[<000000005c213625>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
---
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The reason of this memory leak is tty_ldisc_receive_buf() and tiocsti()
can access the h4->rx_skb concurrently by calling
hci_uart_tty_receive(), so the rx_skb be overwritten without
deallocating. There used to be an spin_lock in hci_uart_tty_receive(),
but it was removed by commit 7649ffaff1cfe(Bluetooth: Remove useless
rx_lock spinlock).
I don’t have that commit in my Linus’ tree. Where is it?
The commit message claims that hci_uart_tty_receive() was only called by
flush_to_ldisc(), but it seems incorrect.
That seems to be a larger problem in the TTY layer if its contract with its users have changed.
Regards
Marcel
Hi Marcel,
It was my typo, the git hash should be 7649faff1cfe4.
Regards,
Phi.
