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Sanity check PVK file fields.

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PVK files with abnormally large length or salt fields can cause an
integer overflow which can result in an OOB read and heap corruption.
However this is an rarely used format and private key files do not
normally come from untrusted sources the security implications not
significant.

Fix by limiting PVK length field to 100K and salt to 10K: these should be
more than enough to cover any files encountered in practice.

Issue reported by Guido Vranken.

Reviewed-by: Rich Salz <rsalz@openssl.org>
This commit is contained in:
Dr. Stephen Henson 2016-03-03 23:37:36 +00:00
parent 0b2fc9286f
commit 5f57abe2b1
1 changed files with 7 additions and 0 deletions
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7
crypto/pem/pvkfmt.c
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@ -119,6 +119,10 @@ static int read_lebn(const unsigned char **in, unsigned int nbyte, BIGNUM **r)
# define MS_PVKMAGIC 0xb0b5f11eL
/* Salt length for PVK files */
# define PVK_SALTLEN 0x10
/* Maximum length in PVK header */
# define PVK_MAX_KEYLEN 102400
/* Maximum salt length */
# define PVK_MAX_SALTLEN 10240
static EVP_PKEY *b2i_rsa(const unsigned char **in,
unsigned int bitlen, int ispub);
@ -608,6 +612,9 @@ static int do_PVK_header(const unsigned char **in, unsigned int length,
*psaltlen = read_ledword(&p);
*pkeylen = read_ledword(&p);
if (*pkeylen > PVK_MAX_KEYLEN || *psaltlen > PVK_MAX_SALTLEN)
return 0;
if (is_encrypted && !*psaltlen) {
PEMerr(PEM_F_DO_PVK_HEADER, PEM_R_INCONSISTENT_HEADER);
return 0;