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CVE-2022-23479 

Detect attempts to overflow input buffer

If application code hasn't properly sanitised the header_size
for a transport, it is possible for read requests to be issued
which overflow the input buffer. This change detects this
at a low level and bounces the read request.
This commit is contained in:
matt335672 2022-12-07 09:44:56 +00:00
parent cea7313257
commit b1147f5faa
2 changed files with 16 additions and 5 deletions
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19
common/trans.c
View File

@ -309,8 +309,8 @@ trans_check_wait_objs(struct trans *self)
tbus in_sck = (tbus) 0; tbus in_sck = (tbus) 0;
struct trans *in_trans = (struct trans *) NULL; struct trans *in_trans = (struct trans *) NULL;
int read_bytes = 0; int read_bytes = 0;
int to_read = 0; unsigned int to_read = 0;
int read_so_far = 0; unsigned int read_so_far = 0;
int rv = 0; int rv = 0;
enum xrdp_source cur_source; enum xrdp_source cur_source;
@ -375,13 +375,24 @@ trans_check_wait_objs(struct trans *self)
} }
else if (self->trans_can_recv(self, self->sck, 0)) else if (self->trans_can_recv(self, self->sck, 0))
{ {
/* CVE-2022-23479 - check a malicious caller hasn't managed
* to set the header_size to an unreasonable value */
if (self->header_size > (unsigned int)self->in_s->size)
{
LOG(LOG_LEVEL_ERROR,
"trans_check_wait_objs: Reading %u bytes beyond buffer",
self->header_size - (unsigned int)self->in_s->size);
self->status = TRANS_STATUS_DOWN;
return 1;
}
cur_source = XRDP_SOURCE_NONE; cur_source = XRDP_SOURCE_NONE;
if (self->si != 0) if (self->si != 0)
{ {
cur_source = self->si->cur_source; cur_source = self->si->cur_source;
self->si->cur_source = self->my_source; self->si->cur_source = self->my_source;
} }
read_so_far = (int) (self->in_s->end - self->in_s->data); read_so_far = self->in_s->end - self->in_s->data;
to_read = self->header_size - read_so_far; to_read = self->header_size - read_so_far;
if (to_read > 0) if (to_read > 0)
@ -421,7 +432,7 @@ trans_check_wait_objs(struct trans *self)
} }
} }
read_so_far = (int) (self->in_s->end - self->in_s->data); read_so_far = self->in_s->end - self->in_s->data;
if (read_so_far == self->header_size) if (read_so_far == self->header_size)
{ {

2
common/trans.h
View File

@ -98,7 +98,7 @@ struct trans
ttrans_data_in trans_data_in; ttrans_data_in trans_data_in;
ttrans_conn_in trans_conn_in; ttrans_conn_in trans_conn_in;
void *callback_data; void *callback_data;
int header_size; unsigned int header_size;
struct stream *in_s; struct stream *in_s;
struct stream *out_s; struct stream *out_s;
char *listen_filename; char *listen_filename;