disk: Fix usdhc driver out-of-bounds array access

MaureenHelm · ioannisg · commit aa9b762d1271 · 2019-08-30T16:57:55.000+02:00
The usdhc driver was incorrectly post-decrementing a do/while loop
iterator, causing an extra iteration of the loop and an out-of-bounds
array access. Change the iterator to decrement within the loop instead.

Tested samples/subsys/fs/fat_fs on the mimxrt1050_evk board.

Coverity-CID: 203403

Signed-off-by: Maureen Helm &lt;maureen.helm@nxp.com&gt;
diff --git a/subsys/disk/disk_access_usdhc.c b/subsys/disk/disk_access_usdhc.c
@@ -1101,7 +1101,8 @@ static int usdhc_cmd_rsp(struct usdhc_priv *priv)
 						((cmd->response[i - 2U] &
 						0xFF000000U) >> 24U);
 				}
-			} while (i--);
+				i--;
+			} while (i);
 		}
 	}
 	/* check response error flag */

Original file line number	Diff line number	Diff line change
`@@ -1101,7 +1101,8 @@ static int usdhc_cmd_rsp(struct usdhc_priv *priv)`
`1101`	`1101`	`((cmd->response[i - 2U] &`
`1102`	`1102`	`0xFF000000U) >> 24U);`
`1103`	`1103`	`}`
`1104`		`- } while (i--);`
	`1104`	`+ i--;`
	`1105`	`+ } while (i);`
`1105`	`1106`	`}`
`1106`	`1107`	`}`
`1107`	`1108`	`/* check response error flag */`