Add error message when elf_parser fails on long section names (#537)

Addresses: #532

Co-authored-by: Aditya K <[email protected]>

src/elf.rs

@@ -1188,6 +1188,7 @@ mod test {
             // FIXME consts::{ELFCLASS32, ELFDATA2MSB, ET_REL},
             consts::{ELFCLASS32, ELFDATA2MSB, ET_REL},
             types::{Elf64Ehdr, Elf64Shdr},
+            SECTION_NAME_LENGTH_MAXIMUM,
         },
         error::ProgramResult,
         fuzz::fuzz,
@@ -1966,4 +1967,17 @@ mod test {
         LittleEndian::write_i32(&mut elf_bytes[0x1064..0x1068], 5);
         ElfExecutable::load(&elf_bytes, loader()).expect("validation failed");
     }
+
+    #[test]
+    fn test_long_section_name() {
+        let elf_bytes = std::fs::read("tests/elfs/long_section_name.so").unwrap();
+        assert_error!(
+            NewParser::parse(&elf_bytes),
+            "FailedToParse(\"Section or symbol name `{}` is longer than `{}` bytes\")",
+            ".bss.__rust_no_alloc_shim_is_unstable"
+                .get(0..SECTION_NAME_LENGTH_MAXIMUM)
+                .unwrap(),
+            SECTION_NAME_LENGTH_MAXIMUM
+        );
+    }
 }

src/elf_parser/mod.rs

@@ -8,7 +8,8 @@ use std::{fmt, mem, ops::Range, slice};
 use crate::{ArithmeticOverflow, ErrCheckedArithmetic};
 use {consts::*, types::*};
 
-const SECTION_NAME_LENGTH_MAXIMUM: usize = 16;
+/// Maximum length of section name allowed.
+pub const SECTION_NAME_LENGTH_MAXIMUM: usize = 16;
 const SYMBOL_NAME_LENGTH_MAXIMUM: usize = 64;
 
 /// Error definitions
@@ -26,6 +27,9 @@ pub enum ElfParserError {
     /// Section or symbol name is not UTF8 or too long
     #[error("invalid string")]
     InvalidString,
+    /// Section or symbol name is too long
+    #[error("Section or symbol name `{0}` is longer than `{1}` bytes")]
+    StringTooLong(String, usize),
     /// An index or memory range does exeed its boundaries
     #[error("value out of bounds")]
     OutOfBounds,
@@ -396,7 +400,12 @@ impl<'a> Elf64<'a> {
             .iter()
             .position(|byte| *byte == 0x00)
             .and_then(|string_length| unterminated_string_bytes.get(0..string_length))
-            .ok_or(ElfParserError::InvalidString)
+            .ok_or_else(|| {
+                ElfParserError::StringTooLong(
+                    String::from_utf8_lossy(unterminated_string_bytes).to_string(),
+                    maximum_length,
+                )
+            })
     }
 
     /// Returns the string corresponding to the given `sh_name`

src/elf_parser_glue.rs

@@ -527,6 +527,7 @@ impl From<ElfParserError> for ElfError {
         match err {
             ElfParserError::InvalidSectionHeader
             | ElfParserError::InvalidString
+            | ElfParserError::StringTooLong(_, _)
             | ElfParserError::InvalidSize
             | ElfParserError::Overlap
             | ElfParserError::SectionNotInOrder