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CIFS: fix use-after-free of the lease keys

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The request buffers are freed right before copying the pointers.
Use the func args instead which are identical and still valid.

Simple reproducer (requires KASAN enabled) on a cifs mount:

echo foo > foo ; tail -f foo & rm foo

Cc: <stable@vger.kernel.org> # 4.20
Fixes: 179e44d49c ("smb3: add tracepoint for sending lease break responses to server")
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Paulo Alcantara <palcantara@suse.de>
This commit is contained in:
Aurelien Aptel 2019-01-31 13:46:07 +01:00 committed by Steve French
parent 082aaa8700
commit d339adc12a
1 changed files with 2 additions and 2 deletions
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4
fs/cifs/smb2pdu.c
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@ -4441,8 +4441,8 @@ SMB2_lease_break(const unsigned int xid, struct cifs_tcon *tcon,
rc = cifs_send_recv(xid, ses, &rqst, &resp_buf_type, flags, &rsp_iov);
cifs_small_buf_release(req);
please_key_low = (__u64 *)req->LeaseKey;
please_key_high = (__u64 *)(req->LeaseKey+8);
please_key_low = (__u64 *)lease_key;
please_key_high = (__u64 *)(lease_key+8);
if (rc) {
cifs_stats_fail_inc(tcon, SMB2_OPLOCK_BREAK_HE);
trace_smb3_lease_err(le32_to_cpu(lease_state), tcon->tid,