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scsi: target/iscsi: Make iscsit_map_iovec() more robust 

Make the code for mapping an iovec more robust by checking the bounds of
the allocated iovec. This patch avoids that the following crash occurs if a
map attempt is made that exceeds the bounds of the iovec that is being
mapped:

BUG: unable to handle kernel NULL pointer dereference at 00000000
00000014
RIP: 0010:iscsit_map_iovec+0x120/0x190 [iscsi_target_mod]
Call Trace:
 iscsit_get_rx_pdu+0x8a2/0xe00 [iscsi_target_mod]
 iscsi_target_rx_thread+0x6e/0xa0 [iscsi_target_mod]
 kthread+0x109/0x140

Cc: Mike Christie <mchristi@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Bart Van Assche 2019-04-02 12:58:14 -07:00 committed by Martin K. Petersen
parent 0ca650c13b
commit 2e39f1c906
1 changed files with 36 additions and 14 deletions
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50
drivers/target/iscsi/iscsi_target.c
View File

@ -573,7 +573,8 @@ iscsit_xmit_nondatain_pdu(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
return 0;
}
static int iscsit_map_iovec(struct iscsi_cmd *, struct kvec *, u32, u32);
static int iscsit_map_iovec(struct iscsi_cmd *cmd, struct kvec *iov, int nvec,
u32 data_offset, u32 data_length);
static void iscsit_unmap_iovec(struct iscsi_cmd *);
static u32 iscsit_do_crypto_hash_sg(struct ahash_request *, struct iscsi_cmd *,
u32, u32, u32, u8 *);
@ -604,7 +605,8 @@ iscsit_xmit_datain_pdu(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
*header_digest);
}
iov_ret = iscsit_map_iovec(cmd, &cmd->iov_data[1],
iov_ret = iscsit_map_iovec(cmd, &cmd->iov_data[iov_count],
cmd->orig_iov_data_count - (iov_count + 2),
datain->offset, datain->length);
if (iov_ret < 0)
return -1;
@ -886,13 +888,10 @@ EXPORT_SYMBOL(iscsit_reject_cmd);
* Map some portion of the allocated scatterlist to an iovec, suitable for
* kernel sockets to copy data in/out.
*/
static int iscsit_map_iovec(
struct iscsi_cmd *cmd,
struct kvec *iov,
u32 data_offset,
u32 data_length)
static int iscsit_map_iovec(struct iscsi_cmd *cmd, struct kvec *iov, int nvec,
u32 data_offset, u32 data_length)
{
u32 i = 0;
u32 i = 0, orig_data_length = data_length;
struct scatterlist *sg;
unsigned int page_off;
@ -901,9 +900,12 @@ static int iscsit_map_iovec(
*/
u32 ent = data_offset / PAGE_SIZE;
if (!data_length)
return 0;
if (ent >= cmd->se_cmd.t_data_nents) {
pr_err("Initial page entry out-of-bounds\n");
return -1;
goto overflow;
}
sg = &cmd->se_cmd.t_data_sg[ent];
@ -913,7 +915,12 @@ static int iscsit_map_iovec(
cmd->first_data_sg_off = page_off;
while (data_length) {
u32 cur_len = min_t(u32, data_length, sg->length - page_off);
u32 cur_len;
if (WARN_ON_ONCE(!sg || i >= nvec))
goto overflow;
cur_len = min_t(u32, data_length, sg->length - page_off);
iov[i].iov_base = kmap(sg_page(sg)) + sg->offset + page_off;
iov[i].iov_len = cur_len;
@ -927,6 +934,16 @@ static int iscsit_map_iovec(
cmd->kmapped_nents = i;
return i;
overflow:
pr_err("offset %d + length %d overflow; %d/%d; sg-list:\n",
data_offset, orig_data_length, i, nvec);
for_each_sg(cmd->se_cmd.t_data_sg, sg,
cmd->se_cmd.t_data_nents, i) {
pr_err("[%d] off %d len %d\n",
i, sg->offset, sg->length);
}
return -1;
}
static void iscsit_unmap_iovec(struct iscsi_cmd *cmd)
@ -1576,8 +1593,8 @@ iscsit_get_dataout(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
rx_size += payload_length;
iov = &cmd->iov_data[0];
iov_ret = iscsit_map_iovec(cmd, iov, be32_to_cpu(hdr->offset),
payload_length);
iov_ret = iscsit_map_iovec(cmd, iov, cmd->orig_iov_data_count - 2,
be32_to_cpu(hdr->offset), payload_length);
if (iov_ret < 0)
return -1;
@ -1597,6 +1614,7 @@ iscsit_get_dataout(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
rx_size += ISCSI_CRC_LEN;
}
WARN_ON_ONCE(iov_count > cmd->orig_iov_data_count);
rx_got = rx_data(conn, &cmd->iov_data[0], iov_count, rx_size);
iscsit_unmap_iovec(cmd);
@ -1862,6 +1880,7 @@ static int iscsit_handle_nop_out(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
rx_size += ISCSI_CRC_LEN;
}
WARN_ON_ONCE(niov > ARRAY_SIZE(cmd->iov_misc));
rx_got = rx_data(conn, &cmd->iov_misc[0], niov, rx_size);
if (rx_got != rx_size) {
ret = -1;
@ -2267,6 +2286,7 @@ iscsit_handle_text_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
rx_size += ISCSI_CRC_LEN;
}
WARN_ON_ONCE(niov > ARRAY_SIZE(iov));
rx_got = rx_data(conn, &iov[0], niov, rx_size);
if (rx_got != rx_size)
goto reject;
@ -2581,8 +2601,9 @@ static int iscsit_handle_immediate_data(
BUG_ON(cmd->write_data_done > cmd->se_cmd.data_length);
rx_size = min(cmd->se_cmd.data_length - cmd->write_data_done, length);
iov_ret = iscsit_map_iovec(cmd, cmd->iov_data, cmd->write_data_done,
rx_size);
iov_ret = iscsit_map_iovec(cmd, cmd->iov_data,
cmd->orig_iov_data_count - 2,
cmd->write_data_done, rx_size);
if (iov_ret < 0)
return IMMEDIATE_DATA_CANNOT_RECOVER;
@ -2618,6 +2639,7 @@ static int iscsit_handle_immediate_data(
rx_size += ISCSI_CRC_LEN;
}
WARN_ON_ONCE(iov_count > cmd->orig_iov_data_count);
rx_got = rx_data(conn, &cmd->iov_data[0], iov_count, rx_size);
iscsit_unmap_iovec(cmd);