multiboot2: fix possible panics for elf sections

Author: phip1611

multiboot2/Changelog.md

@@ -1,15 +1,18 @@
 # CHANGELOG for crate `multiboot2`
 
 ## 0.15.1 (2023-03-18)
-- **BREAKING** `MemoryMapTag::all_memory_areas` was renamed to `memory_areas`
+- **BREAKING** `MemoryMapTag::all_memory_areas()` was renamed to `memory_areas`
   and now returns `MemoryAreaIter` instead of
   `impl Iterator<Item = &MemoryArea>`. Experience showed that its better to
   return the specific iterator whenever possible.
-- **BREAKING** `MemoryMapTag::memory_areas` was renamed to
+- **BREAKING** `MemoryMapTag::memory_areas()` was renamed to
   `available_memory_areas`
   (_Sorry for the breaking changes in a minor release, but I just stumbled upon
   this und since the last breaking release was just yesterday, users have to
   deal with changes anyway._)
+- **BREAKING** `ElfSection::name()` now returns a Result instead of just the
+  value. This prevents possible panics.
+- fix: prevent a possible panic in `ElfSection::section_type()`
 
 ## 0.15.0 (2023-03-17)
 - **BREAKING** MSRV is 1.56.1

multiboot2/src/elf_sections.rs

@@ -1,6 +1,8 @@
 use crate::tag_type::Tag;
 use crate::TagType;
 use core::fmt::{Debug, Formatter};
+use std::str::Utf8Error;
+use derive_more::Display;
 
 /// This tag contains section header table from an ELF kernel.
 ///
@@ -178,7 +180,10 @@ impl ElfSection {
             11 => ElfSectionType::DynamicLoaderSymbolTable,
             0x6000_0000..=0x6FFF_FFFF => ElfSectionType::EnvironmentSpecific,
             0x7000_0000..=0x7FFF_FFFF => ElfSectionType::ProcessorSpecific,
-            _ => panic!(),
+            e => {
+                log::error!("Unknown section type {e:x}. Treating as ElfSectionType::Unused");
+                ElfSectionType::Unused
+            }
         }
     }
 
@@ -188,7 +193,7 @@ impl ElfSection {
     }
 
     /// Read the name of the section.
-    pub fn name(&self) -> &str {
+    pub fn name(&self) -> Result<&str, Utf8Error> {
         use core::{slice, str};
 
         let name_ptr = unsafe { self.string_table().offset(self.get().name_index() as isize) };
@@ -202,7 +207,7 @@ impl ElfSection {
             len as usize
         };
 
-        str::from_utf8(unsafe { slice::from_raw_parts(name_ptr, strlen) }).unwrap()
+        str::from_utf8(unsafe { slice::from_raw_parts(name_ptr, strlen) })
     }
 
     /// Get the physical start address of the section.
@@ -246,15 +251,15 @@ impl ElfSection {
         match self.entry_size {
             40 => unsafe { &*(self.inner as *const ElfSectionInner32) },
             64 => unsafe { &*(self.inner as *const ElfSectionInner64) },
-            _ => panic!(),
+            s => panic!("Unexpected entry size: {s}"),
         }
     }
 
     unsafe fn string_table(&self) -> *const u8 {
         let addr = match self.entry_size {
             40 => (*(self.string_section as *const ElfSectionInner32)).addr as usize,
             64 => (*(self.string_section as *const ElfSectionInner64)).addr as usize,
-            _ => panic!(),
+            s => panic!("Unexpected entry size: {s}"),
         };
         (addr + self.offset) as *const _
     }