afs: Deal with an empty callback array
Servers may send a callback array that is the same size as
the FID array, or an empty array. If the callback count is
0, the code would attempt to read (fid_count * 12) bytes of
data, which would fail and result in an unmarshalling error.
This would lead to stale data for remotely modified files
or directories.
Store the callback array size in the internal afs_call
structure and use that to determine the amount of data to
read.
Signed-off-by: Marc Dionne <marc.dionne@auristor.com>
diff --git a/fs/afs/cmservice.c b/fs/afs/cmservice.c
index 2edbdcb..3062cce 100644
--- a/fs/afs/cmservice.c
+++ b/fs/afs/cmservice.c
@@ -187,7 +187,6 @@
struct afs_callback *cb;
struct afs_server *server;
__be32 *bp;
- u32 tmp;
int ret, loop;
_enter("{%u}", call->unmarshall);
@@ -249,9 +248,9 @@
if (ret < 0)
return ret;
- tmp = ntohl(call->tmp);
- _debug("CB count: %u", tmp);
- if (tmp != call->count && tmp != 0)
+ call->count2 = ntohl(call->tmp);
+ _debug("CB count: %u", call->count2);
+ if (call->count2 != call->count && call->count2 != 0)
return -EBADMSG;
call->offset = 0;
call->unmarshall++;
@@ -259,14 +258,14 @@
case 4:
_debug("extract CB array");
ret = afs_extract_data(call, call->buffer,
- call->count * 3 * 4, false);
+ call->count2 * 3 * 4, false);
if (ret < 0)
return ret;
_debug("unmarshall CB array");
cb = call->request;
bp = call->buffer;
- for (loop = call->count; loop > 0; loop--, cb++) {
+ for (loop = call->count2; loop > 0; loop--, cb++) {
cb->version = ntohl(*bp++);
cb->expiry = ntohl(*bp++);
cb->type = ntohl(*bp++);
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 5dfa569..8499870 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -90,7 +90,10 @@
unsigned request_size; /* size of request data */
unsigned reply_max; /* maximum size of reply */
unsigned first_offset; /* offset into mapping[first] */
- unsigned last_to; /* amount of mapping[last] */
+ union {
+ unsigned last_to; /* amount of mapping[last] */
+ unsigned count2; /* count used in unmarshalling */
+ };
unsigned char unmarshall; /* unmarshalling phase */
bool incoming; /* T if incoming call */
bool send_pages; /* T if data from mapping should be sent */