Fix

CosmWasm · Sep 26, 2024 · cf413c5 · cf413c5
1 parent 01c3c4e
commit cf413c5
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Showing 3 changed files with 53 additions and 29 deletions.
diff --git a/packages/vm/src/errors/communication_error.rs b/packages/vm/src/errors/communication_error.rs
@@ -25,6 +25,9 @@ pub enum CommunicationError {
         #[from]
         source: RegionValidationError,
     },
+    /// When the contract supplies invalid section data to the host. See also `decode_sections` [crate::sections::decode_sections].
+    #[error("Got an invalid section: {}", msg)]
+    InvalidSection { msg: String },
     /// Whenever UTF-8 bytes cannot be decoded into a unicode string, e.g. in String::from_utf8 or str::from_utf8.
     #[error("Cannot decode UTF8 bytes into string: {}", msg)]
     InvalidUtf8 { msg: String },
@@ -56,6 +59,10 @@ impl CommunicationError {
         CommunicationError::InvalidOrder { value }
     }
 
+    pub(crate) fn invalid_section(msg: impl Into<String>) -> Self {
+        CommunicationError::InvalidSection { msg: msg.into() }
+    }
+
     #[allow(dead_code)]
     pub(crate) fn invalid_utf8(msg: impl ToString) -> Self {
         CommunicationError::InvalidUtf8 {

diff --git a/packages/vm/src/imports.rs b/packages/vm/src/imports.rs
@@ -730,9 +730,9 @@ pub fn do_ed25519_batch_verify<
         (EDDSA_PUBKEY_LEN + 4) * MAX_COUNT_ED25519_BATCH,
     )?;
 
-    let messages = decode_sections(&messages);
-    let signatures = decode_sections(&signatures);
-    let public_keys = decode_sections(&public_keys);
+    let messages = decode_sections(&messages)?;
+    let signatures = decode_sections(&signatures)?;
+    let public_keys = decode_sections(&public_keys)?;
 
     let gas_cost = if public_keys.len() == 1 {
         &data.gas_config.ed25519_batch_verify_one_pubkey_cost

diff --git a/packages/vm/src/sections.rs b/packages/vm/src/sections.rs
@@ -1,13 +1,12 @@
 use crate::conversion::to_u32;
-use crate::errors::VmResult;
+use crate::{CommunicationError, VmResult};
 
 /// Decodes sections of data into multiple slices.
 ///
 /// Each encoded section is suffixed by a section length, encoded as big endian uint32.
 ///
-/// See also: `encode_section`.
-#[allow(dead_code)]
-pub fn decode_sections(data: &[u8]) -> Vec<&[u8]> {
+/// See also: [`encode_sections`].
+pub fn decode_sections(data: &[u8]) -> Result<Vec<&[u8]>, CommunicationError> {
     let mut result: Vec<&[u8]> = vec![];
     let mut remaining_len = data.len();
     while remaining_len >= 4 {
@@ -17,11 +16,20 @@ pub fn decode_sections(data: &[u8]) -> Vec<&[u8]> {
             data[remaining_len - 2],
             data[remaining_len - 1],
         ]) as usize;
-        result.push(&data[remaining_len - 4 - tail_len..remaining_len - 4]);
-        remaining_len -= 4 + tail_len;
+        let tail_len_idx = remaining_len - 4; // index of the first byte of the tail length
+        let section_start = tail_len_idx
+            .checked_sub(tail_len)
+            .ok_or_else(|| CommunicationError::invalid_section("section length overflow"))?;
+        result.push(&data[section_start..tail_len_idx]);
+        remaining_len = section_start;
+    }
+    if remaining_len > 0 {
+        return Err(CommunicationError::invalid_section(
+            "extra data outside of any section",
+        ));
     }
     result.reverse();
-    result
+    Ok(result)
 }
 
 /// Encodes multiple sections of data into one vector.
@@ -57,52 +65,61 @@ mod tests {
 
     #[test]
     fn decode_sections_works_for_empty_sections() {
-        let dec = decode_sections(&[]);
+        let dec = decode_sections(&[]).unwrap();
         assert_eq!(dec.len(), 0);
-        let dec = decode_sections(b"\0\0\0\0");
+        let dec = decode_sections(b"\0\0\0\0").unwrap();
         assert_eq!(dec, &[&[0u8; 0]]);
-        let dec = decode_sections(b"\0\0\0\0\0\0\0\0");
+        let dec = decode_sections(b"\0\0\0\0\0\0\0\0").unwrap();
         assert_eq!(dec, &[&[0u8; 0]; 2]);
-        let dec = decode_sections(b"\0\0\0\0\0\0\0\0\0\0\0\0");
+        let dec = decode_sections(b"\0\0\0\0\0\0\0\0\0\0\0\0").unwrap();
         assert_eq!(dec, &[&[0u8; 0]; 3]);
-        // ignores "trailing" stuff
-        let dec = decode_sections(b"\0\0\0\0\0\0\0\0\0\0\0");
-        assert_eq!(dec, &[&[0u8; 0]; 2]);
     }
 
     #[test]
     fn decode_sections_works_for_one_element() {
-        let dec = decode_sections(b"\xAA\0\0\0\x01");
+        let dec = decode_sections(b"\xAA\0\0\0\x01").unwrap();
         assert_eq!(dec, &[vec![0xAA]]);
-        let dec = decode_sections(b"\xAA\xBB\0\0\0\x02");
+        let dec = decode_sections(b"\xAA\xBB\0\0\0\x02").unwrap();
         assert_eq!(dec, &[vec![0xAA, 0xBB]]);
-        let dec = decode_sections(b"\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\0\0\x01\x15");
+        let dec = decode_sections(b"\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\0\0\x01\x15").unwrap();
         assert_eq!(dec, &[vec![0x9D; 277]]);
     }
 
     #[test]
     fn decode_sections_works_for_two_elements() {
         let data = b"\xAA\0\0\0\x01\xBB\xCC\0\0\0\x02".to_vec();
-        assert_eq!(decode_sections(&data), &[vec![0xAA], vec![0xBB, 0xCC]]);
+        assert_eq!(
+            decode_sections(&data).unwrap(),
+            &[vec![0xAA], vec![0xBB, 0xCC]]
+        );
         let data = b"\xDE\xEF\x62\0\0\0\x03\0\0\0\0".to_vec();
-        assert_eq!(decode_sections(&data), &[vec![0xDE, 0xEF, 0x62], vec![]]);
+        assert_eq!(
+            decode_sections(&data).unwrap(),
+            &[vec![0xDE, 0xEF, 0x62], vec![]]
+        );
         let data = b"\0\0\0\0\xDE\xEF\x62\0\0\0\x03".to_vec();
-        assert_eq!(decode_sections(&data), &[vec![], vec![0xDE, 0xEF, 0x62]]);
+        assert_eq!(
+            decode_sections(&data).unwrap(),
+            &[vec![], vec![0xDE, 0xEF, 0x62]]
+        );
         let data = b"\0\0\0\0\0\0\0\0".to_vec();
-        assert_eq!(decode_sections(&data), &[vec![0u8; 0], vec![]]);
+        assert_eq!(decode_sections(&data).unwrap(), &[vec![0u8; 0], vec![]]);
         let data = b"\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\0\0\0\x13\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\x9D\0\0\x01\x15".to_vec();
-        assert_eq!(decode_sections(&data), &[vec![0xFF; 19], vec![0x9D; 277]]);
+        assert_eq!(
+            decode_sections(&data).unwrap(),
+            &[vec![0xFF; 19], vec![0x9D; 277]]
+        );
     }
 
     #[test]
     fn decode_sections_works_for_multiple_elements() {
-        let dec = decode_sections(b"\xAA\0\0\0\x01");
+        let dec = decode_sections(b"\xAA\0\0\0\x01").unwrap();
         assert_eq!(dec, &[vec![0xAA]]);
-        let dec = decode_sections(b"\xAA\0\0\0\x01\xDE\xDE\0\0\0\x02");
+        let dec = decode_sections(b"\xAA\0\0\0\x01\xDE\xDE\0\0\0\x02").unwrap();
         assert_eq!(dec, &[vec![0xAA], vec![0xDE, 0xDE]]);
-        let dec = decode_sections(b"\xAA\0\0\0\x01\xDE\xDE\0\0\0\x02\0\0\0\0");
+        let dec = decode_sections(b"\xAA\0\0\0\x01\xDE\xDE\0\0\0\x02\0\0\0\0").unwrap();
         assert_eq!(dec, &[vec![0xAA], vec![0xDE, 0xDE], vec![]]);
-        let dec = decode_sections(b"\xAA\0\0\0\x01\xDE\xDE\0\0\0\x02\0\0\0\0\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\0\0\0\x13");
+        let dec = decode_sections(b"\xAA\0\0\0\x01\xDE\xDE\0\0\0\x02\0\0\0\0\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\0\0\0\x13").unwrap();
         assert_eq!(dec, &[vec![0xAA], vec![0xDE, 0xDE], vec![], vec![0xFF; 19]]);
     }