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RUSTSEC-2021-0003

Buffer overflow in SmallVec::insert_many

Issued
Package
smallvec (crates.io)
Type
Vulnerability
Categories
Keywords
#buffer-overflow #heap-overflow #unsound
Aliases
Details
https://github.com/servo/rust-smallvec/issues/252
CVSS Score
9.8 CRITICAL
CVSS Details
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Patched
  • >=0.6.14, <1.0.0
  • >=1.6.1
Unaffected
  • <0.6.3
Keywords
#buffer-overflow #heap-overflow #unsound
Affected Functions
Version
smallvec::SmallVec::insert_many
  • >=0.6.3, <0.6.14
  • >=1.0.0, <1.6.1

Description

A bug in the SmallVec::insert_many method caused it to allocate a buffer that was smaller than needed. It then wrote past the end of the buffer, causing a buffer overflow and memory corruption on the heap.

This bug was only triggered if the iterator passed to insert_many yielded more items than the lower bound returned from its size_hint method.

The flaw was corrected in smallvec 0.6.14 and 1.6.1, by ensuring that additional space is always reserved for each item inserted. The fix also simplified the implementation of insert_many to use less unsafe code, so it is easier to verify its correctness.

Thank you to Yechan Bae (@Qwaz) and the Rust group at Georgia Tech’s SSLab for finding and reporting this bug.