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cifs: Fix use-after-free on mid_q_entry

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With CIFS_DEBUG_2 enabled, additional debug information is tracked inside each
mid_q_entry struct, however cifs_save_when_sent may use the mid_q_entry after it
has been freed from the appropriate callback if the transport layer has very low
latency. Holding the srv_mutex fixes this use-after-free, as cifs_save_when_sent
is called while the srv_mutex is held while the request is sent.

Signed-off-by: Christopher Oo <t-chriso@microsoft.com>
This commit is contained in:
Christopher Oo 2015-06-25 16:10:48 -07:00 committed by Steve French
parent 0a6d0b6412
commit 5fb4e288a0
3 changed files with 16 additions and 0 deletions
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7
fs/cifs/cifssmb.c
View File

@ -696,7 +696,9 @@ cifs_echo_callback(struct mid_q_entry *mid)
{
struct TCP_Server_Info *server = mid->callback_data;
mutex_lock(&server->srv_mutex);
DeleteMidQEntry(mid);
mutex_unlock(&server->srv_mutex);
add_credits(server, 1, CIFS_ECHO_OP);
}
@ -1572,7 +1574,9 @@ cifs_readv_callback(struct mid_q_entry *mid)
}
queue_work(cifsiod_wq, &rdata->work);
mutex_lock(&server->srv_mutex);
DeleteMidQEntry(mid);
mutex_unlock(&server->srv_mutex);
add_credits(server, 1, 0);
}
@ -2032,6 +2036,7 @@ cifs_writev_callback(struct mid_q_entry *mid)
{
struct cifs_writedata *wdata = mid->callback_data;
struct cifs_tcon *tcon = tlink_tcon(wdata->cfile->tlink);
struct TCP_Server_Info *server = tcon->ses->server;
unsigned int written;
WRITE_RSP *smb = (WRITE_RSP *)mid->resp_buf;
@ -2068,7 +2073,9 @@ cifs_writev_callback(struct mid_q_entry *mid)
}
queue_work(cifsiod_wq, &wdata->work);
mutex_lock(&server->srv_mutex);
DeleteMidQEntry(mid);
mutex_unlock(&server->srv_mutex);
add_credits(tcon->ses->server, 1, 0);
}

7
fs/cifs/smb2pdu.c
View File

@ -1626,7 +1626,9 @@ smb2_echo_callback(struct mid_q_entry *mid)
if (mid->mid_state == MID_RESPONSE_RECEIVED)
credits_received = le16_to_cpu(smb2->hdr.CreditRequest);
mutex_lock(&server->srv_mutex);
DeleteMidQEntry(mid);
mutex_unlock(&server->srv_mutex);
add_credits(server, credits_received, CIFS_ECHO_OP);
}
@ -1810,7 +1812,9 @@ smb2_readv_callback(struct mid_q_entry *mid)
cifs_stats_fail_inc(tcon, SMB2_READ_HE);
queue_work(cifsiod_wq, &rdata->work);
mutex_lock(&server->srv_mutex);
DeleteMidQEntry(mid);
mutex_unlock(&server->srv_mutex);
add_credits(server, credits_received, 0);
}
@ -1938,6 +1942,7 @@ smb2_writev_callback(struct mid_q_entry *mid)
{
struct cifs_writedata *wdata = mid->callback_data;
struct cifs_tcon *tcon = tlink_tcon(wdata->cfile->tlink);
struct TCP_Server_Info *server = tcon->ses->server;
unsigned int written;
struct smb2_write_rsp *rsp = (struct smb2_write_rsp *)mid->resp_buf;
unsigned int credits_received = 1;
@ -1977,7 +1982,9 @@ smb2_writev_callback(struct mid_q_entry *mid)
cifs_stats_fail_inc(tcon, SMB2_WRITE_HE);
queue_work(cifsiod_wq, &wdata->work);
mutex_lock(&server->srv_mutex);
DeleteMidQEntry(mid);
mutex_unlock(&server->srv_mutex);
add_credits(tcon->ses->server, credits_received, 0);
}

2
fs/cifs/transport.c
View File

@ -644,7 +644,9 @@ cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
}
spin_unlock(&GlobalMid_Lock);
mutex_lock(&server->srv_mutex);
DeleteMidQEntry(mid);
mutex_unlock(&server->srv_mutex);
return rc;
}