From b96db32fed8dfb2478d7c208f89bf383beed1535 Mon Sep 17 00:00:00 2001 From: Frank Sorenson Date: Thu, 6 Aug 2026 21:41:56 -0500 Subject: [PATCH] cifs: clear tcon after cifsFileInfo_put() in cifs_file_set_size() When the else branch of cifs_file_set_size() finds a writable file handle via find_writable_file(), it borrows tcon and server from the handle's tlink, attempts the handle-based set_file_size() RPC, and then releases the handle with cifsFileInfo_put(). If set_file_size() fails, execution falls through to the path-based fallback, which reuses the borrowed tcon and server under the "if (tcon == NULL)" guard. Since tcon is not NULL at that point, the guard is skipped. If cifsFileInfo_put() dropped the last reference on a tlink that was already removed from the tlink tree (TCON_LINK_IN_TREE cleared, as happens during reconnection or session teardown), cifs_put_tlink() will have freed tcon; the subsequent set_path_size() call is then a use-after-free. Setting tcon = NULL after cifsFileInfo_put() causes the existing guard to take the cifs_sb_tlink() path, which acquires a fresh reference for the path-based operation or fails cleanly if the session is gone. Fixes: 110fee6b9bb5 ("smb: client: fix missing timestamp updates with O_TRUNC") Cc: stable@vger.kernel.org Cc: Paulo Alcantara Signed-off-by: Frank Sorenson Signed-off-by: Paulo Alcantara --- fs/smb/client/inode.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c index cb5515a50f74..d459b6f602ca 100644 --- a/fs/smb/client/inode.c +++ b/fs/smb/client/inode.c @@ -3118,6 +3118,7 @@ int cifs_file_set_size(const unsigned int xid, struct dentry *dentry, size, false); cifs_dbg(FYI, "%s: set_file_size: rc = %d\n", __func__, rc); cifsFileInfo_put(open_file); + tcon = NULL; } }