linux-stable.git/drivers/tty/tty_io.c, branch linux-5.14.y

tty: Fix data race between tiocsti() and flush_to_ldisc()

2021-09-15T08:02:33+00:00

commit bb2853a6a421a052268eee00fd5d3f6b3504b2b1 upstream.

The ops->receive_buf() may be accessed concurrently from these two
functions.  If the driver flushes data to the line discipline
receive_buf() method while tiocsti() is waiting for the
ops->receive_buf() to finish its work, the data race will happen.

For example:
tty_ioctl			|tty_ldisc_receive_buf
 ->tioctsi			| ->tty_port_default_receive_buf
				|  ->tty_ldisc_receive_buf
   ->hci_uart_tty_receive	|   ->hci_uart_tty_receive
    ->h4_recv                   |    ->h4_recv

In this case, the h4 receive buffer will be overwritten by the
latecomer, and we will lost the data.

Hence, change tioctsi() function to use the exclusive lock interface
from tty_buffer to avoid the data race.

Reported-by: syzbot+97388eb9d31b997fe1d0@syzkaller.appspotmail.com
Reviewed-by: Jiri Slaby 
Signed-off-by: Nguyen Dinh Phi 
Link: https://lore.kernel.org/r/20210823000641.2082292-1-phind.uet@gmail.com
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

tty: fix kernel-doc for {start,stop}_tty

2021-05-20T14:59:14+00:00

Commit f9e053dcfc02 (tty: Serialize tty flow control changes with
flow_lock) renamed start_tty to __start_tty and stop_tty to __stop_tty
and introduced new start_tty and stop_tty. But it left kernel-doc
comments on the old locations:
 tty_io.c:785: warning: expecting prototype for stop_tty(). Prototype was for __stop_tty() instead
 tty_io.c:816: warning: expecting prototype for start_tty(). Prototype was for __start_tty() instead

Fix that by moving the comments to appropriate locations.

Signed-off-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20210519072153.3859-4-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman

tty: fix kernel-doc for tty_{read,write}

2021-05-20T14:59:14+00:00

After commits a9cbbb80e3e7 (tty: avoid using vfs_iocb_iter_write() for
redirected console writes) and dd78b0c483e3 (tty: implement read_iter),
the tty_read and tty_write kernel-doc comments don't match the code:
 tty_io.c:931: warning: Function parameter or member 'iocb' not described in 'tty_read'
 tty_io.c:931: warning: Function parameter or member 'to' not described in 'tty_read'
 tty_io.c:931: warning: Excess function parameter 'file' description in 'tty_read'
 tty_io.c:931: warning: Excess function parameter 'buf' description in 'tty_read'
 tty_io.c:931: warning: Excess function parameter 'count' description in 'tty_read'
 tty_io.c:931: warning: Excess function parameter 'ppos' description in 'tty_read'
 tty_io.c:1115: warning: Function parameter or member 'iocb' not described in 'file_tty_write'
 tty_io.c:1115: warning: Function parameter or member 'from' not described in 'file_tty_write'
 tty_io.c:1115: warning: expecting prototype for tty_write(). Prototype was for file_tty_write() instead

Fix them to correspond the reality, i.e. the switch from read/write to
read_iter/write_iter.

Cc: Linus Torvalds 
Signed-off-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20210519072153.3859-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman

tty: tty_io: Remove return in void function

2021-05-13T16:29:13+00:00

Remove return in void function, reported by checkpatch.pl.

Signed-off-by: Xiaofei Tan 
Link: https://lore.kernel.org/r/1620811585-18582-15-git-send-email-tanxiaofei@huawei.com
Signed-off-by: Greg Kroah-Hartman

tty: tty_io: Delete a blank line before EXPORT_SYMBOL(foo)

2021-05-13T16:29:13+00:00

Delete a blank line before EXPORT_SYMBOL(foo) so that EXPORT_SYMBOL(foo)
immediately follow its function/variable, reported by checkpatch.pl.

Signed-off-by: Xiaofei Tan 
Link: https://lore.kernel.org/r/1620811585-18582-14-git-send-email-tanxiaofei@huawei.com
Signed-off-by: Greg Kroah-Hartman

tty: tty_io: Fix an issue of code indent for conditional statements

2021-05-13T16:29:13+00:00

Fix an issue of code indent for conditional statements,reported by
checkpatch.pl.

Signed-off-by: Xiaofei Tan 
Link: https://lore.kernel.org/r/1620811585-18582-13-git-send-email-tanxiaofei@huawei.com
Signed-off-by: Greg Kroah-Hartman

tty: tty_io: Remove the repeated word 'can'

2021-05-13T16:29:13+00:00

Remove the repeated word 'can' following advice of checkpatch.pl

Signed-off-by: Xiaofei Tan 
Link: https://lore.kernel.org/r/1620811585-18582-12-git-send-email-tanxiaofei@huawei.com
Signed-off-by: Greg Kroah-Hartman

tty: tty_io: Fix coding style issues of block comments

2021-05-13T16:29:13+00:00

Fix coding style issues of block comments, reported by checkpatch.pl.
Besides, add a period at the end of the sentenses.

Signed-off-by: Xiaofei Tan 
Link: https://lore.kernel.org/r/1620811585-18582-11-git-send-email-tanxiaofei@huawei.com
Signed-off-by: Greg Kroah-Hartman

tty: tty_io: Fix trailing whitespace issues

2021-05-13T16:29:13+00:00

Fix trailing whitespace issues, reported by checkpatch.pl.

Signed-off-by: Xiaofei Tan 
Link: https://lore.kernel.org/r/1620811585-18582-10-git-send-email-tanxiaofei@huawei.com
Signed-off-by: Greg Kroah-Hartman

tty: tty_io: Fix spaces required around that ':'

2021-05-13T16:29:13+00:00

Fix spaces required around that ':', reported by checkpatch.pl.

Signed-off-by: Xiaofei Tan 
Link: https://lore.kernel.org/r/1620811585-18582-9-git-send-email-tanxiaofei@huawei.com
Signed-off-by: Greg Kroah-Hartman