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Fix BIO_f_cipher() flushing 

If an error occurs during a flush on a BIO_f_cipher() then in some cases
we could get into an infinite loop. We add a check to make sure we are
making progress during flush and exit if not.

This issue was reported by Octavio Galland who also demonstrated an
infinite loop in CMS encryption as a result of this bug.

The security team has assessed this issue as not a CVE. This occurs on
*encryption* only which is typically processing trusted data. We are not
aware of a way to trigger this with untrusted data.

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19918)
This commit is contained in:
Matt Caswell 2022-12-06 14:18:53 +00:00 committed by Tomas Mraz
parent 42061268ee
commit e51dd6ee1b
1 changed files with 8 additions and 1 deletions
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9
crypto/evp/bio_enc.c
View File

@ -297,6 +297,7 @@ static long enc_ctrl(BIO *b, int cmd, long num, void *ptr)
int i;
EVP_CIPHER_CTX **c_ctx;
BIO *next;
int pend;
ctx = BIO_get_data(b);
next = BIO_next(b);
@ -332,8 +333,14 @@ static long enc_ctrl(BIO *b, int cmd, long num, void *ptr)
/* do a final write */
again:
while (ctx->buf_len != ctx->buf_off) {
pend = ctx->buf_len - ctx->buf_off;
i = enc_write(b, NULL, 0);
if (i < 0)
/*
* i should never be > 0 here because we didn't ask to write any
* new data. We stop if we get an error or we failed to make any
* progress writing pending data.
*/
if (i < 0 || (ctx->buf_len - ctx->buf_off) == pend)
return i;
}