[Intel-wired-lan] [PATCH net] i40e: limit the DDP profile count returned by the firmware

[Linkui Xiao]

From: Linkui Xiao <xiaolinkui@xxxxxxxxxx>

i40e_aq_get_ddp_list() writes into a I40E_PROFILE_LIST_SIZE buffer,
which is sized for I40E_MAX_PROFILE_NUM (16) i40e_profile_info entries
plus the 4 byte p_count header. i40e_ddp_does_profile_exist() and
i40e_ddp_does_profile_overlap() then loop over profile_list->p_count
without bounding it, so a firmware reporting more than 16 profiles makes
both helpers walk past the end of the on-stack buff[] and compare
against whatever happens to follow it on the stack.

Clamp the count to the number of entries the buffer can actually hold
and make the loop counter unsigned to match the field type.

Fixes: cdc594e00370 ("i40e: Implement DDP support in i40e driver")
Signed-off-by: Linkui Xiao <xiaolinkui@xxxxxxxxxx>
---
 drivers/net/ethernet/intel/i40e/i40e_ddp.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_ddp.c b/drivers/net/ethernet/intel/i40e/i40e_ddp.c
index daa9f2c42f70..1d6d8b3835a3 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_ddp.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_ddp.c
@@ -55,7 +55,7 @@ static int i40e_ddp_does_profile_exist(struct i40e_hw *hw,
 	struct i40e_ddp_profile_list *profile_list;
 	u8 buff[I40E_PROFILE_LIST_SIZE];
 	int status;
-	int i;
+	u32 i, p_count;
 
 	status = i40e_aq_get_ddp_list(hw, buff, I40E_PROFILE_LIST_SIZE, 0,
 				      NULL);
@@ -63,7 +63,12 @@ static int i40e_ddp_does_profile_exist(struct i40e_hw *hw,
 		return -1;
 
 	profile_list = (struct i40e_ddp_profile_list *)buff;
-	for (i = 0; i < profile_list->p_count; i++) {
+	/* Never walk past the end of buff[], the profile count reported by
+	 * the firmware is not guaranteed to fit into the buffer we gave it.
+	 */
+	p_count = min_t(u32, profile_list->p_count, I40E_MAX_PROFILE_NUM);
+
+	for (i = 0; i < p_count; i++) {
 		if (i40e_ddp_profiles_eq(pinfo, &profile_list->p_info[i]))
 			return 1;
 	}
@@ -110,7 +115,7 @@ static int i40e_ddp_does_profile_overlap(struct i40e_hw *hw,
 	struct i40e_ddp_profile_list *profile_list;
 	u8 buff[I40E_PROFILE_LIST_SIZE];
 	int status;
-	int i;
+	u32 i, p_count;
 
 	status = i40e_aq_get_ddp_list(hw, buff, I40E_PROFILE_LIST_SIZE, 0,
 				      NULL);
@@ -118,7 +123,12 @@ static int i40e_ddp_does_profile_overlap(struct i40e_hw *hw,
 		return -EIO;
 
 	profile_list = (struct i40e_ddp_profile_list *)buff;
-	for (i = 0; i < profile_list->p_count; i++) {
+	/* Never walk past the end of buff[], the profile count reported by
+	 * the firmware is not guaranteed to fit into the buffer we gave it.
+	 */
+	p_count = min_t(u32, profile_list->p_count, I40E_MAX_PROFILE_NUM);
+
+	for (i = 0; i < p_count; i++) {
 		if (i40e_ddp_profiles_overlap(pinfo,
 					      &profile_list->p_info[i]))
 			return 1;
-- 
2.25.1