From 2e39f1c9064d54e51e939ce5f3cf34527ef5603f Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Tue, 2 Apr 2019 12:58:14 -0700 Subject: [PATCH] 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 Cc: Hannes Reinecke Cc: Christoph Hellwig Cc: Nicholas Bellinger Signed-off-by: Bart Van Assche Signed-off-by: Martin K. Petersen --- drivers/target/iscsi/iscsi_target.c | 50 +++++++++++++++++++++-------- 1 file changed, 36 insertions(+), 14 deletions(-) diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c index 8cdea25f1377..f01cdae54277 100644 --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -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); -- 2.30.2