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Fixed memory leak in userauth_publickey().

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userauth_publickey_fromfile() reads the key from a
file using file_read_publickey() which returns two
allocated strings, the decoded key and the key
method (such as "ssh-dss").  The latter can be
derived from the former but returning both avoids a
later allocation while doing so.

Older versions of userauth_publickey_fromfile() used
this method string directly but when
userauth_publickey() was factored out of
userauth_publickey_fromfile() it derived the method
from the key itself.  This resulted in the method
being allocated twice.

This fix, which maintains the optimisation that
avoids an extra allocation, changes
userauth_publickey() so it doesn't allocate and
derive the method when userauth_pblc_method already
has a value.

Signed-off-by: Alexander Lamaison <awl03@doc.ic.ac.uk>
This commit is contained in:
Alexander Lamaison
2009-12-30 04:15:28 +00:00
parent 7926c9cfaa
commit 73e37b3b49
1 changed files with 25 additions and 9 deletions
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34
src/userauth.c
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@@ -41,6 +41,8 @@
#include <ctype.h>
#include <stdio.h>
#include <assert.h>
/* Needed for struct iovec on some platforms */
#ifdef HAVE_SYS_UIO_H
#include <sys/uio.h>
@@ -469,7 +471,10 @@ libssh2_userauth_password_ex(LIBSSH2_SESSION *session, const char *username,
*
* Read a public key from an id_???.pub style file
*
* Returns an allocated string in *pubkeydata on success.
* Returns an allocated string containing the decoded key in *pubkeydata
* on success.
* Returns an allocated string containing the key method (e.g. "ssh-dss")
* in method on success.
*/
static int
file_read_publickey(LIBSSH2_SESSION * session, unsigned char **method,
@@ -948,16 +953,27 @@ userauth_publickey(LIBSSH2_SESSION *session,
memset(&session->userauth_pblc_packet_requirev_state, 0,
sizeof(session->userauth_pblc_packet_requirev_state));
session->userauth_pblc_method_len = _libssh2_ntohu32(pubkeydata);
session->userauth_pblc_method =
LIBSSH2_ALLOC(session, session->userauth_pblc_method_len);
/*
* As an optimisation, userauth_publickey_fromfile reuses a
* previously allocated copy of the method name to avoid an extra
* allocation/free.
* For other uses, we allocate and populate it here.
*/
if (!session->userauth_pblc_method) {
libssh2_error(session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate memory for public key data", 0);
return -1;
session->userauth_pblc_method_len = _libssh2_ntohu32(pubkeydata);
session->userauth_pblc_method =
LIBSSH2_ALLOC(session, session->userauth_pblc_method_len);
if (!session->userauth_pblc_method) {
libssh2_error(session, LIBSSH2_ERROR_ALLOC,
"Unable to allocate memory for public key "
"data", 0);
return -1;
}
memcpy(session->userauth_pblc_method, pubkeydata + 4,
session->userauth_pblc_method_len);
}
memcpy(session->userauth_pblc_method, pubkeydata + 4,
session->userauth_pblc_method_len);
assert( /* preallocated method len should match what we expect */
session->userauth_pblc_method_len == _libssh2_ntohu32(pubkeydata));
/*
* 45 = packet_type(1) + username_len(4) + servicename_len(4) +