releases/3.18.3/powerpc-fix-bad-null-pointer-check-in-udbg_uart_getc_poll.patch

   1 From cd32e2dcc9de6c27ecbbfc0e2079fb64b42bad5f Mon Sep 17 00:00:00 2001
   2 From: Anton Blanchard <anton@samba.org>
   3 Date: Tue, 11 Nov 2014 09:12:28 +1100
   4 Subject: powerpc: Fix bad NULL pointer check in udbg_uart_getc_poll()
   5
   6 From: Anton Blanchard <anton@samba.org>
   7
   8 commit cd32e2dcc9de6c27ecbbfc0e2079fb64b42bad5f upstream.
   9
  10 We have some code in udbg_uart_getc_poll() that tries to protect
  11 against a NULL udbg_uart_in, but gets it all wrong.
  12
  13 Found with the LLVM static analyzer (scan-build).
  14
  15 Fixes: 309257484cc1 ("powerpc: Cleanup udbg_16550 and add support for LPC PIO-only UARTs")
  16 Signed-off-by: Anton Blanchard <anton@samba.org>
  17 [mpe: Add some newlines for readability while we're here]
  18 Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
  19 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  20
  21 ---
  22  arch/powerpc/kernel/udbg_16550.c |    6 +++++-
  23  1 file changed, 5 insertions(+), 1 deletion(-)
  24
  25 --- a/arch/powerpc/kernel/udbg_16550.c
  26 +++ b/arch/powerpc/kernel/udbg_16550.c
  27 @@ -69,8 +69,12 @@ static void udbg_uart_putc(char c)
  28
  29  static int udbg_uart_getc_poll(void)
  30  {
  31 -       if (!udbg_uart_in || !(udbg_uart_in(UART_LSR) & LSR_DR))
  32 +       if (!udbg_uart_in)
  33 +               return -1;
  34 +
  35 +       if (!(udbg_uart_in(UART_LSR) & LSR_DR))
  36                 return udbg_uart_in(UART_RBR);
  37 +
  38         return -1;
  39  }
  40