From 1baff47b81f94f9231c91236aa511420d0e266b9 Mon Sep 17 00:00:00 2001 From: Akif Date: Fri, 17 Apr 2026 23:57:09 +0530 Subject: [PATCH] ksmbd: fix use-after-free in smb2_open during durable reconnect In smb2_open, the call to ksmbd_put_durable_fd(fp) drops the reference to the durable file descriptor early during the durable reconnect process. If an error occurs subsequently (eg, ksmbd_iov_pin_rsp fails) or a scavenger accesses the file, it leads to a use-after-free when accessing fp properties (eg fp->create_time). Move the single put to the end of the function below err_out2 so fp stays valid until smb2_open returns. Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2") Signed-off-by: Akif Acked-by: Namjae Jeon Signed-off-by: Steve French --- fs/smb/server/smb2pdu.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index ee32e61b6d3c..395007c82831 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -3014,29 +3014,23 @@ int smb2_open(struct ksmbd_work *work) if (dh_info.reconnected == true) { rc = smb2_check_durable_oplock(conn, share, dh_info.fp, lc, sess->user, name); - if (rc) { - ksmbd_put_durable_fd(dh_info.fp); + if (rc) goto err_out2; - } rc = ksmbd_reopen_durable_fd(work, dh_info.fp); - if (rc) { - ksmbd_put_durable_fd(dh_info.fp); + if (rc) goto err_out2; - } fp = dh_info.fp; if (ksmbd_override_fsids(work)) { rc = -ENOMEM; - ksmbd_put_durable_fd(dh_info.fp); goto err_out2; } file_info = FILE_OPENED; rc = ksmbd_vfs_getattr(&fp->filp->f_path, &stat); - ksmbd_put_durable_fd(fp); if (rc) goto err_out2; @@ -3806,6 +3800,9 @@ int smb2_open(struct ksmbd_work *work) ksmbd_debug(SMB, "Error response: %x\n", rsp->hdr.Status); } + if (dh_info.reconnected) + ksmbd_put_durable_fd(dh_info.fp); + kfree(name); kfree(lc);