printf: Check precision before writing into stdout (#6511)

* Add a new error type InvalidPrecision

* check if the precision is valid before writing to stdout when it is signedInt, unsigned, or float

* add tests for invalid precision check

* add tests for invalid precision check

* fix possible cross-platform issue that code failing to pass on some tests

* uucore/format: inline var in format string

---------

Co-authored-by: Daniel Hofstetter <[email protected]>

Author: Kev1n8

src/uucore/src/lib/features/format/mod.rs

@@ -62,6 +62,7 @@ pub enum FormatError {
     TooManySpecs(Vec<u8>),
     NeedAtLeastOneSpec(Vec<u8>),
     WrongSpecType,
+    InvalidPrecision(String),
 }
 
 impl Error for FormatError {}
@@ -91,6 +92,7 @@ impl Display for FormatError {
                 "format '{}' has no % directive",
                 String::from_utf8_lossy(s)
             ),
+            Self::InvalidPrecision(precision) => write!(f, "invalid precision: '{precision}'"),
             // TODO: Error message below needs some work
             Self::WrongSpecType => write!(f, "wrong % directive type was given"),
             Self::IoError(_) => write!(f, "io error"),

src/uucore/src/lib/features/format/spec.rs

@@ -374,6 +374,10 @@ impl Spec {
                 let precision = resolve_asterisk(*precision, &mut args)?.unwrap_or(0);
                 let i = args.get_i64();
 
+                if precision as u64 > i32::MAX as u64 {
+                    return Err(FormatError::InvalidPrecision(precision.to_string()));
+                }
+
                 num_format::SignedInt {
                     width,
                     precision,
@@ -393,6 +397,10 @@ impl Spec {
                 let precision = resolve_asterisk(*precision, &mut args)?.unwrap_or(0);
                 let i = args.get_u64();
 
+                if precision as u64 > i32::MAX as u64 {
+                    return Err(FormatError::InvalidPrecision(precision.to_string()));
+                }
+
                 num_format::UnsignedInt {
                     variant: *variant,
                     precision,
@@ -415,6 +423,10 @@ impl Spec {
                 let precision = resolve_asterisk(*precision, &mut args)?.unwrap_or(6);
                 let f = args.get_f64();
 
+                if precision as u64 > i32::MAX as u64 {
+                    return Err(FormatError::InvalidPrecision(precision.to_string()));
+                }
+
                 num_format::Float {
                     width,
                     precision,

tests/by-util/test_printf.rs

@@ -774,3 +774,21 @@ fn format_spec_zero_string_fails() {
     // It is invalid to have the format spec '%0s'
     new_ucmd!().args(&["%0s", "3"]).fails().code_is(1);
 }
+
+#[test]
+fn invalid_precision_fails() {
+    // It is invalid to have length of output string greater than i32::MAX
+    new_ucmd!()
+        .args(&["%.*d", "2147483648", "0"])
+        .fails()
+        .stderr_is("printf: invalid precision: '2147483648'\n");
+}
+
+#[test]
+fn float_invalid_precision_fails() {
+    // It is invalid to have length of output string greater than i32::MAX
+    new_ucmd!()
+        .args(&["%.*f", "2147483648", "0"])
+        .fails()
+        .stderr_is("printf: invalid precision: '2147483648'\n");
+}