diff options
author | Anthony Mallet <anthony.mallet@laas.fr> | 2020-03-12 14:31:01 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-03-17 20:27:08 +0100 |
commit | b401f8c4f492cbf74f3f59c9141e5be3071071bb (patch) | |
tree | 32bd10b6ee9ac9e1bbc262b9ceb107d1d978f4b0 /drivers/i2c/muxes/i2c-mux-pca9541.c | |
parent | USB: cdc-acm: fix close_delay and closing_wait units in TIOCSSERIAL (diff) | |
download | linux-b401f8c4f492cbf74f3f59c9141e5be3071071bb.tar.xz linux-b401f8c4f492cbf74f3f59c9141e5be3071071bb.zip |
USB: cdc-acm: fix rounding error in TIOCSSERIAL
By default, tty_port_init() initializes those parameters to a multiple
of HZ. For instance in line 69 of tty_port.c:
port->close_delay = (50 * HZ) / 100;
https://github.com/torvalds/linux/blob/master/drivers/tty/tty_port.c#L69
With e.g. CONFIG_HZ = 250 (as this is the case for Ubuntu 18.04
linux-image-4.15.0-37-generic), the default setting for close_delay is
thus 125.
When ioctl(fd, TIOCGSERIAL, &s) is executed, the setting returned in
user space is '12' (125/10). When ioctl(fd, TIOCSSERIAL, &s) is then
executed with the same setting '12', the value is interpreted as '120'
which is different from the current setting and a EPERM error may be
raised by set_serial_info() if !CAP_SYS_ADMIN.
https://github.com/torvalds/linux/blob/master/drivers/usb/class/cdc-acm.c#L919
Fixes: ba2d8ce9db0a6 ("cdc-acm: implement TIOCSSERIAL to avoid blocking close(2)")
Signed-off-by: Anthony Mallet <anthony.mallet@laas.fr>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200312133101.7096-2-anthony.mallet@laas.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/i2c/muxes/i2c-mux-pca9541.c')
0 files changed, 0 insertions, 0 deletions