From: Xiubo Li <lixiubo@xxxxxxxxxxxxxxxxxxxx>
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 reporduce very easy and some
not. The following is the crash core trace:
[ 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@xxxxxxxxxxxxxxxxxx>
Tested-by: Damien Le Moal <damien.lemoal@xxxxxxx>
Signed-off-by: Xiubo Li <lixiubo@xxxxxxxxxxxxxxxxxxxx>
---
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 2f1fa92..3b25ef3 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -563,7 +563,7 @@ 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)) {
@@ -636,7 +636,7 @@ 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);
@@ -840,10 +840,9 @@ 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);
@@ -862,11 +861,10 @@ 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,
@@ -879,8 +877,8 @@ 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
--
1.8.3.1
