On 24. 06. 20, 11:34, Greg Kroah-Hartman wrote: > On Sat, Jun 13, 2020 at 08:52:18PM +0800, Xiyu Yang wrote: >> uart_port_startup() invokes uart_port_lock(), which returns a reference >> of the uart_port object if increases the refcount of the uart_state >> object successfully or returns NULL if fails. >> >> However, uart_port_startup() don't take the return value of >> uart_port_lock() as the new uart_port object to "uport" and use the old >> "uport" instead to balance refcount in uart_port_unlock(), which may >> cause a redundant decrement of refcount occurred when the new "uport" >> equals to NULL and then cause a potential memory leak. >> >> Fix this issue by update the "uport" object to the return value of >> uart_port_lock() when invoking uart_port_lock(). >> >> Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx> >> Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx> >> --- >> drivers/tty/serial/serial_core.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c >> index 57840cf90388..968fd619aec0 100644 >> --- a/drivers/tty/serial/serial_core.c >> +++ b/drivers/tty/serial/serial_core.c >> @@ -205,7 +205,7 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, >> if (!page) >> return -ENOMEM; >> >> - uart_port_lock(state, flags); >> + uport = uart_port_lock(state, flags); > > How is this a different pointer than you originally had? Was this patch sent twice? As I had very same questions on the other one, but never received a feedback: https://lore.kernel.org/linux-serial/bf6c1e7b-3dc6-aba6-955a-fee351a6d800@xxxxxxxx/ Oh, wait: this is uart_port_startup, I commented on the uart_shutdown one. But whatever, I would scratch both of them. > And if it is a different pointer, shouldn't you be calling this function > and using the pointer much earlier in the function instead of just here? > > Can you trigger a problem that this patch solves? If so, how? thanks, -- js suse labs
