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powerpc: Bad NULL pointer check in udbg_uart_getc_poll

Message ID 1415657548-17802-1-git-send-email-anton@samba.org (mailing list archive)
State Accepted
Delegated to: Michael Ellerman
Headers show

Commit Message

Anton Blanchard Nov. 10, 2014, 10:12 p.m. UTC 
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")
Cc: stable@vger.kernel.org
Signed-off-by: Anton Blanchard <anton@samba.org>
---
 arch/powerpc/kernel/udbg_16550.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
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Patch

diff --git a/arch/powerpc/kernel/udbg_16550.c b/arch/powerpc/kernel/udbg_16550.c
index 6e7c492..3faf393 100644
--- a/arch/powerpc/kernel/udbg_16550.c
+++ b/arch/powerpc/kernel/udbg_16550.c
@@ -69,7 +69,9 @@  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;
 }