From 33f736187d08f6bc822117629f263b97d3df4165 Mon Sep 17 00:00:00 2001 From: Shyam Prasad N Date: Thu, 22 Jun 2023 18:16:03 +0000 Subject: cifs: prevent use-after-free by freeing the cfile later In smb2_compound_op we have a possible use-after-free which can cause hard to debug problems later on. This was revealed during stress testing with KASAN enabled kernel. Fixing it by moving the cfile free call to a few lines below, after the usage. Fixes: 76894f3e2f71 ("cifs: improve symlink handling for smb2+") Reviewed-by: Paulo Alcantara (SUSE) Signed-off-by: Shyam Prasad N Signed-off-by: Steve French --- fs/smb/client/smb2inode.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'fs') diff --git a/fs/smb/client/smb2inode.c b/fs/smb/client/smb2inode.c index 163a03298430..7e3ac4cb4efa 100644 --- a/fs/smb/client/smb2inode.c +++ b/fs/smb/client/smb2inode.c @@ -398,9 +398,6 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon, rsp_iov); finished: - if (cfile) - cifsFileInfo_put(cfile); - SMB2_open_free(&rqst[0]); if (rc == -EREMCHG) { pr_warn_once("server share %s deleted\n", tcon->tree_name); @@ -529,6 +526,9 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon, break; } + if (cfile) + cifsFileInfo_put(cfile); + if (rc && err_iov && err_buftype) { memcpy(err_iov, rsp_iov, 3 * sizeof(*err_iov)); memcpy(err_buftype, resp_buftype, 3 * sizeof(*err_buftype)); -- cgit v1.2.3