[PATCH 1/1] ccs: Make (non-)use of uninitialised variables more robust

* [PATCH 1/1] ccs: Make (non-)use of uninitialised variables more robust
@ 2021-01-05 12:49 Sakari Ailus
  2021-01-05 16:18 ` Hans Verkuil
  0 siblings, 1 reply; 3+ messages in thread
From: Sakari Ailus @ 2021-01-05 12:49 UTC (permalink / raw)
  To: linux-media; +Cc: Hans Verkuil

GCC with W=2 level of kernel compiler warnings warns about the use of
uninitialised variables in a few locations. While these uninitialised
variables were not used in reality, this still produced compiler warnings.

Address this by assigning the variables to NULL and checking for NULL in
places it is not expected, returning -EPROTO in that case. This provides
at least some sanity checking at runtime as the compiler appears unable to
do that at compile time.

Reported-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/i2c/ccs/ccs-data.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/media/i2c/ccs/ccs-data.c b/drivers/media/i2c/ccs/ccs-data.c
index 59338a6704af..99b2b515058a 100644
--- a/drivers/media/i2c/ccs/ccs-data.c
+++ b/drivers/media/i2c/ccs/ccs-data.c
@@ -214,7 +214,7 @@ static int ccs_data_parse_regs(struct bin_container *bin,
 			       size_t *__num_regs, const void *payload,
 			       const void *endp, struct device *dev)
 {
-	struct ccs_reg *regs_base, *regs;
+	struct ccs_reg *regs_base = NULL, *regs = NULL;
 	size_t num_regs = 0;
 	u16 addr = 0;
 
@@ -285,6 +285,9 @@ static int ccs_data_parse_regs(struct bin_container *bin,
 		if (!bin->base) {
 			bin_reserve(bin, len);
 		} else if (__regs) {
+			if (!regs)
+				return -EPROTO;
+
 			regs->addr = addr;
 			regs->len = len;
 			regs->value = bin_alloc(bin, len);
@@ -305,8 +308,12 @@ static int ccs_data_parse_regs(struct bin_container *bin,
 	if (__num_regs)
 		*__num_regs = num_regs;
 
-	if (bin->base && __regs)
+	if (bin->base && __regs) {
+		if (!regs_base)
+			return -EPROTO;
+
 		*__regs = regs_base;
+	}
 
 	return 0;
 }
@@ -425,7 +432,7 @@ static int ccs_data_parse_rules(struct bin_container *bin,
 				size_t *__num_rules, const void *payload,
 				const void *endp, struct device *dev)
 {
-	struct ccs_rule *rules_base, *rules = NULL, *next_rule;
+	struct ccs_rule *rules_base = NULL, *rules = NULL, *next_rule = NULL;
 	size_t num_rules = 0;
 	const void *__next_rule = payload;
 	int rval;
@@ -483,6 +490,9 @@ static int ccs_data_parse_rules(struct bin_container *bin,
 			} else {
 				unsigned int i;
 
+				if (!next_rule)
+					return -EPROTO;
+
 				rules = next_rule;
 				next_rule++;
 
@@ -555,6 +565,9 @@ static int ccs_data_parse_rules(struct bin_container *bin,
 		bin_reserve(bin, sizeof(*rules) * num_rules);
 		*__num_rules = num_rules;
 	} else {
+		if (!rules_base)
+			return -EPROTO;
+
 		*__rules = rules_base;
 	}
 
@@ -690,7 +703,7 @@ static int ccs_data_parse_pdaf(struct bin_container *bin, struct ccs_pdaf_pix_lo
 	}
 
 	for (i = 0; i < max_block_type_id; i++) {
-		struct ccs_pdaf_pix_loc_pixel_desc_group *pdgroup;
+		struct ccs_pdaf_pix_loc_pixel_desc_group *pdgroup = NULL;
 		unsigned int j;
 
 		if (!is_contained(__num_pixel_descs, endp))
@@ -721,6 +734,9 @@ static int ccs_data_parse_pdaf(struct bin_container *bin, struct ccs_pdaf_pix_lo
 			if (!bin->base)
 				continue;
 
+			if (!pdgroup)
+				return -EPROTO;
+
 			pdesc = &pdgroup->descs[j];
 			pdesc->pixel_type = __pixel_desc->pixel_type;
 			pdesc->small_offset_x = __pixel_desc->small_offset_x;
-- 
2.29.2


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