From 891e084b26837162b12f841060086a105edde86d Mon Sep 17 00:00:00 2001 From: Alan Coopersmith Date: Fri, 25 Apr 2014 23:02:00 -0700 Subject: [PATCH 03/12] CVE-2014-0210: unvalidated length in _fs_recv_conn_setup() The connection setup reply from the font server can include a list of alternate servers to contact if this font server stops working. The reply specifies a total size of all the font server names, and then provides a list of names. _fs_recv_conn_setup() allocated the specified total size for copying the names to, but didn't check to make sure it wasn't copying more data to that buffer than the size it had allocated. Reported-by: Ilja Van Sprundel Signed-off-by: Alan Coopersmith Reviewed-by: Adam Jackson Reviewed-by: Matthieu Herrb --- src/fc/fserve.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/src/fc/fserve.c b/src/fc/fserve.c index 3585951..aa9acdb 100644 --- a/src/fc/fserve.c +++ b/src/fc/fserve.c @@ -2784,7 +2784,7 @@ _fs_recv_conn_setup (FSFpePtr conn) int ret = FSIO_ERROR; fsConnSetup *setup; FSFpeAltPtr alts; - int i, alt_len; + unsigned int i, alt_len; int setup_len; char *alt_save, *alt_names; @@ -2811,8 +2811,9 @@ _fs_recv_conn_setup (FSFpePtr conn) } if (setup->num_alternates) { + size_t alt_name_len = setup->alternate_len << 2; alts = malloc (setup->num_alternates * sizeof (FSFpeAltRec) + - (setup->alternate_len << 2)); + alt_name_len); if (alts) { alt_names = (char *) (setup + 1); @@ -2821,10 +2822,25 @@ _fs_recv_conn_setup (FSFpePtr conn) { alts[i].subset = alt_names[0]; alt_len = alt_names[1]; + if (alt_len >= alt_name_len) { + /* + * Length is longer than setup->alternate_len + * told us to allocate room for, assume entire + * alternate list is corrupted. + */ +#ifdef DEBUG + fprintf (stderr, + "invalid alt list (length %lx >= %lx)\n", + (long) alt_len, (long) alt_name_len); +#endif + free(alts); + return FSIO_ERROR; + } alts[i].name = alt_save; memcpy (alt_save, alt_names + 2, alt_len); alt_save[alt_len] = '\0'; alt_save += alt_len + 1; + alt_name_len -= alt_len + 1; alt_names += _fs_pad_length (alt_len + 2); } conn->numAlts = setup->num_alternates; -- 1.7.10