[PATCH 3.14 18/77] powerpc: Fix bad NULL pointer check in udbg_uart_getc_poll()

Greg Kroah-Hartman
2015-01-14T07:35:31Z

From: Anton Blanchard <anton@samba.org>

commit cd32e2dcc9de6c27ecbbfc0e2079fb64b42bad5f upstream.

We have some code in udbg_uart_getc_poll() that tries to protect
against a NULL udbg_uart_in, but gets it all wrong.

Found with the LLVM static analyzer (scan-build).

Fixes: 309257484cc1 ("powerpc: Cleanup udbg_16550 and add support for LPC PIO-only UARTs")
Signed-off-by: Anton Blanchard <anton@samba.org>
[mpe: Add some newlines for readability while we're here]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/powerpc/kernel/udbg_16550.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

--- a/arch/powerpc/kernel/udbg_16550.c
+++ b/arch/powerpc/kernel/udbg_16550.c
@@ -69,8 +69,12 @@ static void udbg_uart_putc(char c)

static int udbg_uart_getc_poll(void)
{
- if (!udbg_uart_in || !(udbg_uart_in(UART_LSR) & LSR_DR))
+ if (!udbg_uart_in)
+ return -1;
+
+ if (!(udbg_uart_in(UART_LSR) & LSR_DR))
return udbg_uart_in(UART_RBR);
+
return -1;
}