Avoid theoretical overflows in EVP_EncodeUpdate.

See also upstream's 172c6e1e14defe7d49d62f5fc9ea6a79b225424f, but note our
values have different types. In particular, because we put in_len in a size_t
and C implicitly requires that all valid buffers' lengths fit in a ptrdiff_t
(signed), the overflow was impossible, assuming EVP_ENCODE_CTX::length is
untouched externally.

More importantly, this function is stuck taking an int output and has no return
value, so the only plausible contract is the caller is responsible for ensuring
the length fits anyway. Indeed, callers all call EVP_EncodeUpdate in bounded
chunks, so upstream's analysis is off.

Anyway, in theory that logic could locally overflow, so tweak it slightly. Tidy
up some of the variable names while I'm here.

Change-Id: Ifa78707cc26c11e0d67019918a028531b3d6738c
Reviewed-on: https://boringssl-review.googlesource.com/7847
Reviewed-by: Adam Langley <agl@google.com>
1 file changed
tree: 5da0c4fd46b015aad3fa6f38c9f99feca1a3bd32
  1. .github/
  2. crypto/
  3. decrepit/
  4. fuzz/
  5. include/
  6. ssl/
  7. tool/
  8. util/
  9. .clang-format
  10. .gitignore
  11. BUILDING.md
  12. CMakeLists.txt
  13. codereview.settings
  15. FUZZING.md
  18. PORTING.md
  19. README.md
  20. STYLE.md


BoringSSL is a fork of OpenSSL that is designed to meet Google's needs.

Although BoringSSL is an open source project, it is not intended for general use, as OpenSSL is. We don't recommend that third parties depend upon it. Doing so is likely to be frustrating because there are no guarantees of API or ABI stability.

Programs ship their own copies of BoringSSL when they use it and we update everything as needed when deciding to make API changes. This allows us to mostly avoid compromises in the name of compatibility. It works for us, but it may not work for you.

BoringSSL arose because Google used OpenSSL for many years in various ways and, over time, built up a large number of patches that were maintained while tracking upstream OpenSSL. As Google's product portfolio became more complex, more copies of OpenSSL sprung up and the effort involved in maintaining all these patches in multiple places was growing steadily.

Currently BoringSSL is the SSL library in Chrome/Chromium, Android (but it's not part of the NDK) and a number of other apps/programs.

There are other files in this directory which might be helpful: