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scsi: libcxgbi: fix skb use after free 

skb->data is assigned to task->hdr in cxgbi_conn_alloc_pdu(),
skb gets freed after tx but task->hdr is still dereferenced in
iscsi_tcp_task_xmit() to avoid this call skb_get() after allocating skb
and free the skb in cxgbi_cleanup_task() or before allocating new skb in
cxgbi_conn_alloc_pdu().

Signed-off-by: Varun Prakash <varun@chelsio.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Varun Prakash 2017-05-16 19:23:44 +05:30 committed by Martin K. Petersen
parent b19775e478
commit 75b61250bf
2 changed files with 26 additions and 15 deletions
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25
drivers/scsi/cxgbi/libcxgbi.c
View File

@ -1873,6 +1873,11 @@ int cxgbi_conn_alloc_pdu(struct iscsi_task *task, u8 opcode)
tcp_task->dd_data = tdata;
task->hdr = NULL;
if (tdata->skb) {
kfree_skb(tdata->skb);
tdata->skb = NULL;
}
if (SKB_MAX_HEAD(cdev->skb_tx_rsvd) > (512 * MAX_SKB_FRAGS) &&
(opcode == ISCSI_OP_SCSI_DATA_OUT ||
(opcode == ISCSI_OP_SCSI_CMD &&
@ -1890,6 +1895,7 @@ int cxgbi_conn_alloc_pdu(struct iscsi_task *task, u8 opcode)
return -ENOMEM;
}
skb_get(tdata->skb);
skb_reserve(tdata->skb, cdev->skb_tx_rsvd);
task->hdr = (struct iscsi_hdr *)tdata->skb->data;
task->hdr_max = SKB_TX_ISCSI_PDU_HEADER_MAX; /* BHS + AHS */
@ -2035,9 +2041,9 @@ int cxgbi_conn_xmit_pdu(struct iscsi_task *task)
unsigned int datalen;
int err;
if (!skb) {
if (!skb || cxgbi_skcb_test_flag(skb, SKCBF_TX_DONE)) {
log_debug(1 << CXGBI_DBG_ISCSI | 1 << CXGBI_DBG_PDU_TX,
"task 0x%p, skb NULL.\n", task);
"task 0x%p, skb 0x%p\n", task, skb);
return 0;
}
@ -2050,7 +2056,6 @@ int cxgbi_conn_xmit_pdu(struct iscsi_task *task)
}
datalen = skb->data_len;
tdata->skb = NULL;
/* write ppod first if using ofldq to write ppod */
if (ttinfo->flags & CXGBI_PPOD_INFO_FLAG_VALID) {
@ -2078,6 +2083,7 @@ int cxgbi_conn_xmit_pdu(struct iscsi_task *task)
pdulen += ISCSI_DIGEST_SIZE;
task->conn->txdata_octets += pdulen;
cxgbi_skcb_set_flag(skb, SKCBF_TX_DONE);
return 0;
}
@ -2086,7 +2092,6 @@ int cxgbi_conn_xmit_pdu(struct iscsi_task *task)
"task 0x%p, skb 0x%p, len %u/%u, %d EAGAIN.\n",
task, skb, skb->len, skb->data_len, err);
/* reset skb to send when we are called again */
tdata->skb = skb;
return err;
}
@ -2094,7 +2099,8 @@ int cxgbi_conn_xmit_pdu(struct iscsi_task *task)
"itt 0x%x, skb 0x%p, len %u/%u, xmit err %d.\n",
task->itt, skb, skb->len, skb->data_len, err);
kfree_skb(skb);
__kfree_skb(tdata->skb);
tdata->skb = NULL;
iscsi_conn_printk(KERN_ERR, task->conn, "xmit err %d.\n", err);
iscsi_conn_failure(task->conn, ISCSI_ERR_XMIT_FAILED);
@ -2113,8 +2119,10 @@ void cxgbi_cleanup_task(struct iscsi_task *task)
tcp_task->dd_data = NULL;
/* never reached the xmit task callout */
if (tdata->skb)
__kfree_skb(tdata->skb);
if (tdata->skb) {
kfree_skb(tdata->skb);
tdata->skb = NULL;
}
task_release_itt(task, task->hdr_itt);
memset(tdata, 0, sizeof(*tdata));
@ -2714,6 +2722,9 @@ EXPORT_SYMBOL_GPL(cxgbi_attr_is_visible);
static int __init libcxgbi_init_module(void)
{
pr_info("%s", version);
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, cb) <
sizeof(struct cxgbi_skb_cb));
return 0;
}

16
drivers/scsi/cxgbi/libcxgbi.h
View File

@ -195,7 +195,8 @@ struct cxgbi_skb_rx_cb {
};
struct cxgbi_skb_tx_cb {
void *l2t;
void *handle;
void *arp_err_handler;
struct sk_buff *wr_next;
};
@ -203,6 +204,7 @@ enum cxgbi_skcb_flags {
SKCBF_TX_NEED_HDR, /* packet needs a header */
SKCBF_TX_MEM_WRITE, /* memory write */
SKCBF_TX_FLAG_COMPL, /* wr completion flag */
SKCBF_TX_DONE, /* skb tx done */
SKCBF_RX_COALESCED, /* received whole pdu */
SKCBF_RX_HDR, /* received pdu header */
SKCBF_RX_DATA, /* received pdu payload */
@ -215,13 +217,13 @@ enum cxgbi_skcb_flags {
};
struct cxgbi_skb_cb {
unsigned char ulp_mode;
unsigned long flags;
unsigned int seq;
union {
struct cxgbi_skb_rx_cb rx;
struct cxgbi_skb_tx_cb tx;
};
unsigned char ulp_mode;
unsigned long flags;
unsigned int seq;
};
#define CXGBI_SKB_CB(skb) ((struct cxgbi_skb_cb *)&((skb)->cb[0]))
@ -374,11 +376,9 @@ static inline void cxgbi_sock_enqueue_wr(struct cxgbi_sock *csk,
cxgbi_skcb_tx_wr_next(skb) = NULL;
/*
* We want to take an extra reference since both us and the driver
* need to free the packet before it's really freed. We know there's
* just one user currently so we use atomic_set rather than skb_get
* to avoid the atomic op.
* need to free the packet before it's really freed.
*/
atomic_set(&skb->users, 2);
skb_get(skb);
if (!csk->wr_pending_head)
csk->wr_pending_head = skb;