Messages in this thread Patch in this message | | | Date | Mon, 12 Oct 2009 19:13:54 +0200 | From | Ingo Molnar <> | Subject | [PATCH] tty, serial: Fix race and NULL check in uart_close() |
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Mon, 12 Oct 2009, Linus Torvalds wrote: > > > > Commit 46d57a449 (which you then bisected to) looks really irritating, > > since it just renamed variables in annoying ways (ie the old "port" is now > > "uport", and there's a new "port" that means something else). That thing > > should have been split up to do the renaming separately, so that a mis-use > > of "port" would have caused a compile error. > > > > I'm not seeing anything obvious. Alan obviously found one bug already. > > Ok, so I did the "do it as two commits", and when doing that (and > being fairly careful at all stages to do everything as no-op > conversions), I get this diff. > > It looks like there is not just the wrong lock, but also a test for > NULL state got dropped by commit 46d57a449. > > NOTE! This patch is against that original bad commit. The flags have since > been moved from 'state' to 'port', so the test for UIF_INITIALIZED is now > > if (port->flags & UIF_INITIALIZED) > > rather than > > if (state->flags & UIF_INITIALIZED) > > and you need to either edit the patch or apply it with "git apply -C1" to > make it apply to current git.
And UIF_INITIALIZED changed to ASYNC_INITIALIZED as well.
> Does that missing test for NULL 'state' fix your oops?
Yes it does! Find below the combo patch against your tree.
Ingo
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Subject: tty, serial: Fix race and NULL check in uart_close() From: Linus Torvalds <torvalds@linux-foundation.org>
Commit 46d57a449aa1 ("serial: use tty_port pointers in the core code") contained two bugs that causes (rare) crashes:
- the rename typoed one site
- a NULL check was missed
Signed-off-by: Ingo Molnar <mingo@elte.hu> --- diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c index 1689bda..dcc7244 100644 --- a/drivers/serial/serial_core.c +++ b/drivers/serial/serial_core.c @@ -1270,6 +1270,9 @@ static void uart_close(struct tty_struct *tty, struct file *filp) BUG_ON(!kernel_locked()); + if (!state) + return; + uport = state->uart_port; port = &state->port; @@ -1316,9 +1319,9 @@ static void uart_close(struct tty_struct *tty, struct file *filp) */ if (port->flags & ASYNC_INITIALIZED) { unsigned long flags; - spin_lock_irqsave(&port->lock, flags); + spin_lock_irqsave(&uport->lock, flags); uport->ops->stop_rx(uport); - spin_unlock_irqrestore(&port->lock, flags); + spin_unlock_irqrestore(&uport->lock, flags); /* * Before we drop DTR, make sure the UART transmitter * has completely drained; this is especially
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