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cifs: prevent use-after-free by freeing the cfile later

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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) <pc@manguebit.com>
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Shyam Prasad N 2023-06-22 18:16:03 +00:00 committed by Steve French
parent f0b6a834a8
commit 33f736187d
1 changed files with 3 additions and 3 deletions
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6
fs/smb/client/smb2inode.c
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@ -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));