From 7d52477ef5e66a43fe54e5737179e4e670db260d Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Thu, 1 May 2014 17:38:23 +0100 Subject: [PATCH] staging: comedi: drivers: correct mode check for i8254_set_mode() The upper bound check on the `mode` parameter of `i8254_set_mode()` and `i8254_mm_set_mode()` is incorrect. The `mode` parameter value consists of a mode number in the range 0 to 5 in bits 3..1 {represented by the constants `I8254_MODE0` (0 << 1) through to `I8254_MODE5` (2 << 1)} ORed with a BCD/binary flag in bit 0 {represented by the constants `I8254_BINARY` (0) and `I8254_BCD` (1)}. The maximum allowed value ought to be `I8254_MODE5 | I8254_BCD` ((5 << 1) | 1), but is currently `I8254_MODE5 | I8254_BINARY` ((5 << 1) | 0). Fix it. None of the comedi drivers use `I8254_BCD` but some of the low-level drivers allow user-space to configure the counter mode, so all legal values ought to be allowed. However, it's pretty unlikely anyone would want to set the counters to count in BCD (binary coded decimal) so the bug is not that significant. Reported-by: Hartley Sweeten Signed-off-by: Ian Abbott Reviewed-by: H Hartley Sweeten Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/8253.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/staging/comedi/drivers/8253.h b/drivers/staging/comedi/drivers/8253.h index fb2c9d905723..5829b46b757b 100644 --- a/drivers/staging/comedi/drivers/8253.h +++ b/drivers/staging/comedi/drivers/8253.h @@ -291,7 +291,7 @@ static inline int i8254_set_mode(unsigned long base_address, if (counter_number > 2) return -1; - if (mode > (I8254_MODE5 | I8254_BINARY)) + if (mode > (I8254_MODE5 | I8254_BCD)) return -1; byte = counter_number << 6; @@ -311,7 +311,7 @@ static inline int i8254_mm_set_mode(void __iomem *base_address, if (counter_number > 2) return -1; - if (mode > (I8254_MODE5 | I8254_BINARY)) + if (mode > (I8254_MODE5 | I8254_BCD)) return -1; byte = counter_number << 6; -- 2.20.1