Check request_buf length first to avoid out-of-bounds read by
req->DialectCount.
[ 3350.990282] BUG: KASAN: slab-out-of-bounds in smb2_handle_negotiate+0x35d7/0x3e60
[ 3350.990282] Read of size 2 at addr ffff88810ad61346 by task kworker/5:0/276
[ 3351.000406] Workqueue: ksmbd-io handle_ksmbd_work
[ 3351.003499] Call Trace:
[ 3351.006473] <TASK>
[ 3351.006473] dump_stack_lvl+0x8d/0xe0
[ 3351.006473] print_report+0xcc/0x620
[ 3351.006473] kasan_report+0x92/0xc0
[ 3351.006473] smb2_handle_negotiate+0x35d7/0x3e60
[ 3351.014760] ksmbd_smb_negotiate_common+0x7a7/0xf00
[ 3351.014760] handle_ksmbd_work+0x3f7/0x12d0
[ 3351.014760] process_one_work+0xa85/0x1780
Signed-off-by: HexRabbit <h3xrabbit@xxxxxxxxx>
---
fs/ksmbd/smb2pdu.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index cb93fd231..972176bff 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -1057,16 +1057,16 @@ int smb2_handle_negotiate(struct ksmbd_work *work)
return rc;
}
- if (req->DialectCount == 0) {
- pr_err("malformed packet\n");
+ smb2_buf_len = get_rfc1002_len(work->request_buf);
+ smb2_neg_size = offsetof(struct smb2_negotiate_req, Dialects);
+ if (smb2_neg_size > smb2_buf_len) {
rsp->hdr.Status = STATUS_INVALID_PARAMETER;
rc = -EINVAL;
goto err_out;
}
- smb2_buf_len = get_rfc1002_len(work->request_buf);
- smb2_neg_size = offsetof(struct smb2_negotiate_req, Dialects);
- if (smb2_neg_size > smb2_buf_len) {
+ if (req->DialectCount == 0) {
+ pr_err("malformed packet\n");
rsp->hdr.Status = STATUS_INVALID_PARAMETER;
rc = -EINVAL;
goto err_out;
--
2.25.1
