From: Dan Gopstein <dgopstein@xxxxxxx>
Two definitions of the ABS (absolute value) macro fail to parenthesize
their parameter properly. This can lead to a bad expansion for
low-precedence expression arguments. Add parens to protect against
troublesome arguments.
For example: ABS(1-2) currently expands to ((1-2) < 0 ? (-1-2) : (1-2))
which evaluates to -3. But the correct expansion would be
((1-2) < 0 ? -(1-2) : (1-2)) which evaluates to 1.
Signed-off-by: Dan Gopstein <dgopstein@xxxxxxx>
---
v1->v2:
* unmangled the patch
* added example to commit text
drivers/media/dvb-frontends/dibx000_common.h | 2 +-
drivers/media/dvb-frontends/mb86a16.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/media/dvb-frontends/dibx000_common.h b/drivers/media/dvb-frontends/dibx000_common.h
index 8784af9..ae60f5d 100644
--- a/drivers/media/dvb-frontends/dibx000_common.h
+++ b/drivers/media/dvb-frontends/dibx000_common.h
@@ -223,7 +223,7 @@ struct dvb_frontend_parametersContext {
#define FE_CALLBACK_TIME_NEVER 0xffffffff
-#define ABS(x) ((x < 0) ? (-x) : (x))
+#define ABS(x) (((x) < 0) ? -(x) : (x))
#define DATA_BUS_ACCESS_MODE_8BIT 0x01
#define DATA_BUS_ACCESS_MODE_16BIT 0x02
diff --git a/drivers/media/dvb-frontends/mb86a16.c b/drivers/media/dvb-frontends/mb86a16.c
index dfe322e..2d921c7 100644
--- a/drivers/media/dvb-frontends/mb86a16.c
+++ b/drivers/media/dvb-frontends/mb86a16.c
@@ -31,7 +31,7 @@
static unsigned int verbose = 5;
module_param(verbose, int, 0644);
-#define ABS(x) ((x) < 0 ? (-x) : (x))
+#define ABS(x) ((x) < 0 ? -(x) : (x))
struct mb86a16_state {
struct i2c_adapter *i2c_adap;
--
2.7.4
