Commit baf57b56 authored by Paul Aurich's avatar Paul Aurich Committed by Steve French
Browse files

cifs: Fix leak when handling lease break for cached root fid 



Handling a lease break for the cached root didn't free the
smb2_lease_break_work allocation, resulting in a leak:

    unreferenced object 0xffff98383a5af480 (size 128):
      comm "cifsd", pid 684, jiffies 4294936606 (age 534.868s)
      hex dump (first 32 bytes):
        c0 ff ff ff 1f 00 00 00 88 f4 5a 3a 38 98 ff ff  ..........Z:8...
        88 f4 5a 3a 38 98 ff ff 80 88 d6 8a ff ff ff ff  ..Z:8...........
      backtrace:
        [<0000000068957336>] smb2_is_valid_oplock_break+0x1fa/0x8c0
        [<0000000073b70b9e>] cifs_demultiplex_thread+0x73d/0xcc0
        [<00000000905fa372>] kthread+0x11c/0x150
        [<0000000079378e4e>] ret_from_fork+0x22/0x30

Avoid this leak by only allocating when necessary.

Fixes: a93864d9 ("cifs: add lease tracking to the cached root fid")
Signed-off-by: default avatarPaul Aurich <paul@darkrain42.org>
CC: Stable <stable@vger.kernel.org> # v4.18+
Reviewed-by: default avatarAurelien Aptel <aaptel@suse.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent bcf87687

fs/cifs/smb2misc.c

+52 −21
Original line number Diff line number Diff line
@@ -508,15 +508,31 @@ cifs_ses_oplock_break(struct work_struct *work) 
	kfree(lw);

}



static void

smb2_queue_pending_open_break(struct tcon_link *tlink, __u8 *lease_key,

			      __le32 new_lease_state)

{

	struct smb2_lease_break_work *lw;



	lw = kmalloc(sizeof(struct smb2_lease_break_work), GFP_KERNEL);

	if (!lw) {

		cifs_put_tlink(tlink);

		return;

	}



	INIT_WORK(&lw->lease_break, cifs_ses_oplock_break);

	lw->tlink = tlink;

	lw->lease_state = new_lease_state;

	memcpy(lw->lease_key, lease_key, SMB2_LEASE_KEY_SIZE);

	queue_work(cifsiod_wq, &lw->lease_break);

}



static bool

smb2_tcon_has_lease(struct cifs_tcon *tcon, struct smb2_lease_break *rsp,

		    struct smb2_lease_break_work *lw)

smb2_tcon_has_lease(struct cifs_tcon *tcon, struct smb2_lease_break *rsp)

{

	bool found;

	__u8 lease_state;

	struct list_head *tmp;

	struct cifsFileInfo *cfile;

	struct cifs_pending_open *open;

	struct cifsInodeInfo *cinode;

	int ack_req = le32_to_cpu(rsp->Flags &

				  SMB2_NOTIFY_BREAK_LEASE_FLAG_ACK_REQUIRED);
@@ -546,22 +562,29 @@ smb2_tcon_has_lease(struct cifs_tcon *tcon, struct smb2_lease_break *rsp, 
		cfile->oplock_level = lease_state;



		cifs_queue_oplock_break(cfile);

		kfree(lw);

		return true;

	}



	found = false;

	return false;

}



static struct cifs_pending_open *

smb2_tcon_find_pending_open_lease(struct cifs_tcon *tcon,

				  struct smb2_lease_break *rsp)

{

	__u8 lease_state = le32_to_cpu(rsp->NewLeaseState);

	int ack_req = le32_to_cpu(rsp->Flags &

				  SMB2_NOTIFY_BREAK_LEASE_FLAG_ACK_REQUIRED);

	struct cifs_pending_open *open;

	struct cifs_pending_open *found = NULL;



	list_for_each_entry(open, &tcon->pending_opens, olist) {

		if (memcmp(open->lease_key, rsp->LeaseKey,

			   SMB2_LEASE_KEY_SIZE))

			continue;



		if (!found && ack_req) {

			found = true;

			memcpy(lw->lease_key, open->lease_key,

			       SMB2_LEASE_KEY_SIZE);

			lw->tlink = cifs_get_tlink(open->tlink);

			queue_work(cifsiod_wq, &lw->lease_break);

			found = open;

		}



		cifs_dbg(FYI, "found in the pending open list\n");
@@ -582,14 +605,7 @@ smb2_is_valid_lease_break(char *buffer) 
	struct TCP_Server_Info *server;

	struct cifs_ses *ses;

	struct cifs_tcon *tcon;

	struct smb2_lease_break_work *lw;



	lw = kmalloc(sizeof(struct smb2_lease_break_work), GFP_KERNEL);

	if (!lw)

		return false;



	INIT_WORK(&lw->lease_break, cifs_ses_oplock_break);

	lw->lease_state = rsp->NewLeaseState;

	struct cifs_pending_open *open;



	cifs_dbg(FYI, "Checking for lease break\n");
@@ -607,11 +623,27 @@ smb2_is_valid_lease_break(char *buffer) 
				spin_lock(&tcon->open_file_lock);

				cifs_stats_inc(

				    &tcon->stats.cifs_stats.num_oplock_brks);

				if (smb2_tcon_has_lease(tcon, rsp, lw)) {

				if (smb2_tcon_has_lease(tcon, rsp)) {

					spin_unlock(&tcon->open_file_lock);

					spin_unlock(&cifs_tcp_ses_lock);

					return true;

				}

				open = smb2_tcon_find_pending_open_lease(tcon,

									 rsp);

				if (open) {

					__u8 lease_key[SMB2_LEASE_KEY_SIZE];

					struct tcon_link *tlink;



					tlink = cifs_get_tlink(open->tlink);

					memcpy(lease_key, open->lease_key,

					       SMB2_LEASE_KEY_SIZE);

					spin_unlock(&tcon->open_file_lock);

					spin_unlock(&cifs_tcp_ses_lock);

					smb2_queue_pending_open_break(tlink,

								      lease_key,

								      rsp->NewLeaseState);

					return true;

				}

				spin_unlock(&tcon->open_file_lock);



				if (tcon->crfid.is_valid &&
@@ -629,7 +661,6 @@ smb2_is_valid_lease_break(char *buffer) 
		}

	}

	spin_unlock(&cifs_tcp_ses_lock);

	kfree(lw);

	cifs_dbg(FYI, "Can not process lease break - no lease matched\n");

	return false;

}

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