diff options
author | Dr. Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com> | 2018-02-21 01:45:14 +0100 |
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committer | Dr. Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com> | 2018-02-26 19:39:43 +0100 |
commit | b3f9b401ab6284e6bbde59dde06736f681f70a9d (patch) | |
tree | bf3f4fe2c9dac85d92321ef250e6794f21d46e96 /crypto/evp | |
parent | 37e62cee3ee50983ecad88813ec11b326efb123a (diff) |
bio_b64.c: prevent base64 filter BIO from decoding out-of-bound data
Fixes #5405, #1381
The base64 filter BIO reads its input in chunks of B64_BLOCK_SIZE bytes.
When processing input in PEM format it can happen in rare cases that
- the trailing PEM marker crosses the boundary of a chunk, and
- the beginning of the following chunk contains valid base64 encoded data.
This happened in issue #5405, where the PEM marker was split into
"-----END CER" and "TIFICATE-----" at the end of the first chunk.
The decoding of the first chunk terminated correctly at the '-' character,
which is treated as an EOF marker, and b64_read() returned. However,
when called the second time, b64_read() read the next chunk and interpreted
the string "TIFICATE" as valid base64 encoded data, adding 6 extra bytes
'4c 81 48 08 04 c4'.
This patch restores the assignment of the error code to 'ctx->cont', which
was deleted accidentally in commit 5562cfaca4f3 and which prevents b64_read()
from reading additional data on subsequent calls.
This issue was observed and reported by Annie Yousar.
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5422)
Diffstat (limited to 'crypto/evp')
-rw-r--r-- | crypto/evp/bio_b64.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/crypto/evp/bio_b64.c b/crypto/evp/bio_b64.c index 538b520264..5ad5a95035 100644 --- a/crypto/evp/bio_b64.c +++ b/crypto/evp/bio_b64.c @@ -330,6 +330,14 @@ static int b64_read(BIO *b, char *out, int outl) (unsigned char *)ctx->tmp, i); ctx->tmp_len = 0; } + /* + * If eof or an error was signalled, then the condition + * 'ctx->cont <= 0' will prevent b64_read() from reading + * more data on subsequent calls. This assignment was + * deleted accidentally in commit 5562cfaca4f3. + */ + ctx->cont = i; + ctx->buf_off = 0; if (i < 0) { ret_code = 0; |