From 3515503322f4819277091839eed46b695096aca5 Mon Sep 17 00:00:00 2001 From: Junyi Liu Date: Mon, 18 May 2026 23:27:19 +0900 Subject: [PATCH] ksmbd: fix durable reconnect error path file lifetime After a durable reconnect succeeds, ksmbd_reopen_durable_fd() republishes the same ksmbd_file into the session volatile-id table. If smb2_open() then takes a later error path, cleanup first calls ksmbd_fd_put(work, fp) and then unconditionally calls ksmbd_put_durable_fd(dh_info.fp). In this case fp and dh_info.fp are the same object. The first put drops the reconnect lookup reference, but the final durable put can run __ksmbd_close_fd(NULL, fp). Because the final close is not session-aware, it can free the file object without removing the volatile-id entry that was just published into the session table. Use the session-aware put for the final reconnect drop when the reconnect had already succeeded and the error path is cleaning up the republished file. Earlier reconnect failures, before fp is assigned to dh_info.fp, keep using the durable-only put path. Fixes: 1baff47b81f9 ("ksmbd: fix use-after-free in smb2_open during durable reconnect") Signed-off-by: Junyi Liu Acked-by: Namjae Jeon Signed-off-by: Steve French --- fs/smb/server/smb2pdu.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index 62d4399a993d..5128a693aca6 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -3804,8 +3804,19 @@ 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); + if (dh_info.reconnected) { + /* + * If reconnect succeeded, fp was republished in the + * session file table. On a later error, ksmbd_fd_put() + * above drops the session reference; drop the durable + * lookup reference through the same session-aware path so + * final close removes the volatile id before freeing fp. + */ + if (rc && fp == dh_info.fp) + ksmbd_fd_put(work, dh_info.fp); + else + ksmbd_put_durable_fd(dh_info.fp); + } kfree(name); kfree(lc);