[PATCH-v4.12.y 0/2] target: stable backports

[PATCH-v4.12.y 0/2] target: stable backports

[Nicholas A. Bellinger]

From: Nicholas Bellinger <nab@linux-iscsi.org>

Hi Greg-KH,

Here are two target-core-user patches for v4.12.y stable, the latter of
which did not apply because it was dependent upon the former.

The series has been cut against v4.12.5.  Please apply at your earliest
convenience.

Thank you.

--nab

Xiubo Li (2):
  tcmu: Fix flushing cmd entry dcache page
  tcmu: Fix possbile memory leak / OOPs when recalculating cmd base size

 drivers/target/target_core_user.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

-- 
1.8.5.3

[PATCH-v4.12.y 1/2] tcmu: Fix flushing cmd entry dcache page

[Nicholas A. Bellinger]

From: Xiubo Li <lixiubo@cmss.chinamobile.com>

commit 9d62bc0e6d79b11e3298e831358155930fb8f5e3 upstream.

When feeding the tcmu's cmd ring, we need to flush the dcache page
for the cmd entry to make sure these kernel stores are visible to
user space mappings of that page.

For the none PAD cmd entry, this will be flushed at the end of the
tcmu_queue_cmd_ring().

Signed-off-by: Xiubo Li <lixiubo@cmss.chinamobile.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 drivers/target/target_core_user.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index beb5f09..c8b63b8 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -699,21 +699,21 @@ static inline size_t tcmu_cmd_get_cmd_size(struct tcmu_cmd *tcmu_cmd,
 		size_t pad_size = head_to_end(cmd_head, udev->cmdr_size);
 
 		entry = (void *) mb + CMDR_OFF + cmd_head;
-		tcmu_flush_dcache_range(entry, sizeof(*entry));
 		tcmu_hdr_set_op(&entry->hdr.len_op, TCMU_OP_PAD);
 		tcmu_hdr_set_len(&entry->hdr.len_op, pad_size);
 		entry->hdr.cmd_id = 0; /* not used for PAD */
 		entry->hdr.kflags = 0;
 		entry->hdr.uflags = 0;
+		tcmu_flush_dcache_range(entry, sizeof(*entry));
 
 		UPDATE_HEAD(mb->cmd_head, pad_size, udev->cmdr_size);
+		tcmu_flush_dcache_range(mb, sizeof(*mb));
 
 		cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
 		WARN_ON(cmd_head != 0);
 	}
 
 	entry = (void *) mb + CMDR_OFF + cmd_head;
-	tcmu_flush_dcache_range(entry, sizeof(*entry));
 	tcmu_hdr_set_op(&entry->hdr.len_op, TCMU_OP_CMD);
 	entry->hdr.cmd_id = tcmu_cmd->cmd_id;
 	entry->hdr.kflags = 0;
-- 
1.8.5.3

[PATCH-v4.12.y 2/2] tcmu: Fix possbile memory leak / OOPs when recalculating cmd base size

[Nicholas A. Bellinger]

From: Xiubo Li <lixiubo@cmss.chinamobile.com>

commit b3743c71b7c33a126d6d8942bb268775987400ec upstream.

For all the entries allocated from the ring cmd area, the memory is
something like the stack memory, which will always reserve the old
data, so the entry->req.iov_bidi_cnt maybe none zero.

On some environments, the crash could be reproduce very easy and some
not. The following is the crash core trace as reported by Damien:

[  240.143969] CPU: 0 PID: 1285 Comm: iscsi_trx Not tainted 4.12.0-rc1+ #3
[  240.150607] Hardware name: ASUS All Series/H87-PRO, BIOS 2104 10/28/2014
[  240.157331] task: ffff8807de4f5800 task.stack: ffffc900047dc000
[  240.163270] RIP: 0010:memcpy_erms+0x6/0x10
[  240.167377] RSP: 0018:ffffc900047dfc68 EFLAGS: 00010202
[  240.172621] RAX: ffffc9065db85540 RBX: ffff8807f7980000 RCX: 0000000000000010
[  240.179771] RDX: 0000000000000010 RSI: ffff8807de574fe0 RDI: ffffc9065db85540
[  240.186930] RBP: ffffc900047dfd30 R08: ffff8807de41b000 R09: 0000000000000000
[  240.194088] R10: 0000000000000040 R11: ffff8807e9b726f0 R12: 00000006565726b0
[  240.201246] R13: ffffc90007612ea0 R14: 000000065657d540 R15: 0000000000000000
[  240.208397] FS:  0000000000000000(0000) GS:ffff88081fa00000(0000) knlGS:0000000000000000
[  240.216510] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  240.222280] CR2: ffffc9065db85540 CR3: 0000000001c0f000 CR4: 00000000001406f0
[  240.229430] Call Trace:
[  240.231887]  ? tcmu_queue_cmd+0x83c/0xa80
[  240.235916]  ? target_check_reservation+0xcd/0x6f0
[  240.240725]  __target_execute_cmd+0x27/0xa0
[  240.244918]  target_execute_cmd+0x232/0x2c0
[  240.249124]  ? __local_bh_enable_ip+0x64/0xa0
[  240.253499]  iscsit_execute_cmd+0x20d/0x270
[  240.257693]  iscsit_sequence_cmd+0x110/0x190
[  240.261985]  iscsit_get_rx_pdu+0x360/0xc80
[  240.267565]  ? iscsi_target_rx_thread+0x54/0xd0
[  240.273571]  iscsi_target_rx_thread+0x9a/0xd0
[  240.279413]  kthread+0x113/0x150
[  240.284120]  ? iscsi_target_tx_thread+0x1e0/0x1e0
[  240.290297]  ? kthread_create_on_node+0x40/0x40
[  240.296297]  ret_from_fork+0x2e/0x40
[  240.301332] Code: 90 90 90 90 90 eb 1e 0f 1f 00 48 89 f8 48 89 d1 48
c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 c3 66 0f 1f 44 00 00 48 89 f8 48
89 d1 <f3> a4 c3 0f 1f 80 00 00 00 00 48 89 f8 48 83 fa 20 72 7e 40 38
[  240.321751] RIP: memcpy_erms+0x6/0x10 RSP: ffffc900047dfc68
[  240.328838] CR2: ffffc9065db85540
[  240.333667] ---[ end trace b7e5354cfb54d08b ]---

To fix this, just memset all the entry memory before using it, and
also to be more readable we adjust the bidi code.

Fixed: fe25cc34795(tcmu: Recalculate the tcmu_cmd size to save cmd area
		memories)
Reported-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
Tested-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
Reported-by: Damien Le Moal <damien.lemoal@wdc.com>
Tested-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Xiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 drivers/target/target_core_user.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index c8b63b8..0580422 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -437,7 +437,7 @@ static int scatter_data_area(struct tcmu_dev *udev,
 			to_offset = get_block_offset_user(udev, dbi,
 					block_remaining);
 			offset = DATA_BLOCK_SIZE - block_remaining;
-			to = (void *)(unsigned long)to + offset;
+			to += offset;
 
 			if (*iov_cnt != 0 &&
 			    to_offset == iov_tail(udev, *iov)) {
@@ -510,7 +510,7 @@ static void gather_data_area(struct tcmu_dev *udev, struct tcmu_cmd *cmd,
 			copy_bytes = min_t(size_t, sg_remaining,
 					block_remaining);
 			offset = DATA_BLOCK_SIZE - block_remaining;
-			from = (void *)(unsigned long)from + offset;
+			from += offset;
 			tcmu_flush_dcache_range(from, copy_bytes);
 			memcpy(to + sg->length - sg_remaining, from,
 					copy_bytes);
@@ -714,10 +714,9 @@ static inline size_t tcmu_cmd_get_cmd_size(struct tcmu_cmd *tcmu_cmd,
 	}
 
 	entry = (void *) mb + CMDR_OFF + cmd_head;
+	memset(entry, 0, command_size);
 	tcmu_hdr_set_op(&entry->hdr.len_op, TCMU_OP_CMD);
 	entry->hdr.cmd_id = tcmu_cmd->cmd_id;
-	entry->hdr.kflags = 0;
-	entry->hdr.uflags = 0;
 
 	/* Handle allocating space from the data area */
 	tcmu_cmd_reset_dbi_cur(tcmu_cmd);
@@ -736,11 +735,10 @@ static inline size_t tcmu_cmd_get_cmd_size(struct tcmu_cmd *tcmu_cmd,
 		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 	}
 	entry->req.iov_cnt = iov_cnt;
-	entry->req.iov_dif_cnt = 0;
 
 	/* Handle BIDI commands */
+	iov_cnt = 0;
 	if (se_cmd->se_cmd_flags & SCF_BIDI) {
-		iov_cnt = 0;
 		iov++;
 		ret = scatter_data_area(udev, tcmu_cmd,
 					se_cmd->t_bidi_data_sg,
@@ -753,8 +751,8 @@ static inline size_t tcmu_cmd_get_cmd_size(struct tcmu_cmd *tcmu_cmd,
 			pr_err("tcmu: alloc and scatter bidi data failed\n");
 			return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 		}
-		entry->req.iov_bidi_cnt = iov_cnt;
 	}
+	entry->req.iov_bidi_cnt = iov_cnt;
 
 	/*
 	 * Recalaulate the command's base size and size according
-- 
1.8.5.3

Re: [PATCH-v4.12.y 0/2] target: stable backports

[Greg-KH]

On Mon, Aug 07, 2017 at 03:11:25AM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> 
> Hi Greg-KH,
> 
> Here are two target-core-user patches for v4.12.y stable, the latter of
> which did not apply because it was dependent upon the former.
> 
> The series has been cut against v4.12.5.  Please apply at your earliest
> convenience.

Now applied, thanks!

greg k-h