From abc7a266a38b3122977bbf9049c61b6297343004 Mon Sep 17 00:00:00 2001 From: Matt Caswell Date: Mon, 27 Apr 2015 15:41:03 +0100 Subject: [PATCH] Clarify logic in BIO_*printf functions The static function dynamically allocates an output buffer if the output grows larger than the static buffer that is normally used. The original logic implied that |currlen| could be greater than |maxlen| which is incorrect (and if so would cause a buffer overrun). Also the original logic would call OPENSSL_malloc to create a dynamic buffer equal to the size of the static buffer, and then immediately call OPENSSL_realloc to make it bigger, rather than just creating a buffer than was big enough in the first place. Thanks to Kevin Wojtysiak (Int3 Solutions) and Paramjot Oberoi (Int3 Solutions) for reporting this issue. Reviewed-by: Andy Polyakov (cherry picked from commit 9d9e37744cd5119f9921315864d1cd28717173cd) --- crypto/bio/b_print.c | 45 +++++++++++++++++++++----------------------- 1 file changed, 21 insertions(+), 24 deletions(-) diff --git a/crypto/bio/b_print.c b/crypto/bio/b_print.c index 452e5cfd95..7c81e25d48 100644 --- a/crypto/bio/b_print.c +++ b/crypto/bio/b_print.c @@ -704,32 +704,29 @@ doapr_outch(char **sbuffer, /* If we haven't at least one buffer, someone has doe a big booboo */ assert(*sbuffer != NULL || buffer != NULL); - if (buffer) { - while (*currlen >= *maxlen) { - if (*buffer == NULL) { - if (*maxlen == 0) - *maxlen = 1024; - *buffer = OPENSSL_malloc(*maxlen); - if (!*buffer) { - /* Panic! Can't really do anything sensible. Just return */ - return; - } - if (*currlen > 0) { - assert(*sbuffer != NULL); - memcpy(*buffer, *sbuffer, *currlen); - } - *sbuffer = NULL; - } else { - *maxlen += 1024; - *buffer = OPENSSL_realloc(*buffer, *maxlen); - if (!*buffer) { - /* Panic! Can't really do anything sensible. Just return */ - return; - } + /* |currlen| must always be <= |*maxlen| */ + assert(*currlen <= *maxlen); + + if (buffer && *currlen == *maxlen) { + *maxlen += 1024; + if (*buffer == NULL) { + *buffer = OPENSSL_malloc(*maxlen); + if (!*buffer) { + /* Panic! Can't really do anything sensible. Just return */ + return; + } + if (*currlen > 0) { + assert(*sbuffer != NULL); + memcpy(*buffer, *sbuffer, *currlen); + } + *sbuffer = NULL; + } else { + *buffer = OPENSSL_realloc(*buffer, *maxlen); + if (!*buffer) { + /* Panic! Can't really do anything sensible. Just return */ + return; } } - /* What to do if *buffer is NULL? */ - assert(*sbuffer != NULL || *buffer != NULL); } if (*currlen < *maxlen) { -- 2.34.1