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authorBo Wu <wubo40@huawei.com>2019-11-20 16:26:17 +0300
committerMartin K. Petersen <martin.petersen@oracle.com>2019-12-10 04:36:28 +0300
commitbba340c79bfe3644829db5c852fdfa9e33837d6d (patch)
treec449179d108f938fa5deacb2920cf14036b5f170 /drivers/scsi
parent5480e299b5ae57956af01d4839c9fc88a465eeab (diff)
downloadlinux-bba340c79bfe3644829db5c852fdfa9e33837d6d.tar.xz
scsi: iscsi: Avoid potential deadlock in iscsi_if_rx func
In iscsi_if_rx func, after receiving one request through iscsi_if_recv_msg func, iscsi_if_send_reply will be called to try to reply to the request in a do-while loop. If the iscsi_if_send_reply function keeps returning -EAGAIN, a deadlock will occur. For example, a client only send msg without calling recvmsg func, then it will result in the watchdog soft lockup. The details are given as follows: sock_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ISCSI); retval = bind(sock_fd, (struct sock addr*) & src_addr, sizeof(src_addr); while (1) { state_msg = sendmsg(sock_fd, &msg, 0); //Note: recvmsg(sock_fd, &msg, 0) is not processed here. } close(sock_fd); watchdog: BUG: soft lockup - CPU#7 stuck for 22s! [netlink_test:253305] Sample time: 4000897528 ns(HZ: 250) Sample stat: curr: user: 675503481560, nice: 321724050, sys: 448689506750, idle: 4654054240530, iowait: 40885550700, irq: 14161174020, softirq: 8104324140, st: 0 deta: user: 0, nice: 0, sys: 3998210100, idle: 0, iowait: 0, irq: 1547170, softirq: 242870, st: 0 Sample softirq: TIMER: 992 SCHED: 8 Sample irqstat: irq 2: delta 1003, curr: 3103802, arch_timer CPU: 7 PID: 253305 Comm: netlink_test Kdump: loaded Tainted: G OE Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 pstate: 40400005 (nZcv daif +PAN -UAO) pc : __alloc_skb+0x104/0x1b0 lr : __alloc_skb+0x9c/0x1b0 sp : ffff000033603a30 x29: ffff000033603a30 x28: 00000000000002dd x27: ffff800b34ced810 x26: ffff800ba7569f00 x25: 00000000ffffffff x24: 0000000000000000 x23: ffff800f7c43f600 x22: 0000000000480020 x21: ffff0000091d9000 x20: ffff800b34eff200 x19: ffff800ba7569f00 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 0001000101000100 x13: 0000000101010000 x12: 0101000001010100 x11: 0001010101010001 x10: 00000000000002dd x9 : ffff000033603d58 x8 : ffff800b34eff400 x7 : ffff800ba7569200 x6 : ffff800b34eff400 x5 : 0000000000000000 x4 : 00000000ffffffff x3 : 0000000000000000 x2 : 0000000000000001 x1 : ffff800b34eff2c0 x0 : 0000000000000300 Call trace: __alloc_skb+0x104/0x1b0 iscsi_if_rx+0x144/0x12bc [scsi_transport_iscsi] netlink_unicast+0x1e0/0x258 netlink_sendmsg+0x310/0x378 sock_sendmsg+0x4c/0x70 sock_write_iter+0x90/0xf0 __vfs_write+0x11c/0x190 vfs_write+0xac/0x1c0 ksys_write+0x6c/0xd8 __arm64_sys_write+0x24/0x30 el0_svc_common+0x78/0x130 el0_svc_handler+0x38/0x78 el0_svc+0x8/0xc Link: https://lore.kernel.org/r/EDBAAA0BBBA2AC4E9C8B6B81DEEE1D6915E3D4D2@dggeml505-mbx.china.huawei.com Signed-off-by: Bo Wu <wubo40@huawei.com> Reviewed-by: Zhiqiang Liu <liuzhiqiang26@huawei.com> Reviewed-by: Lee Duncan <lduncan@suse.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi')
-rw-r--r--drivers/scsi/scsi_transport_iscsi.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 417b868d8735..ed8d9709b9b9 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -24,6 +24,8 @@
#define ISCSI_TRANSPORT_VERSION "2.0-870"
+#define ISCSI_SEND_MAX_ALLOWED 10
+
#define CREATE_TRACE_POINTS
#include <trace/events/iscsi.h>
@@ -3682,6 +3684,7 @@ iscsi_if_rx(struct sk_buff *skb)
struct nlmsghdr *nlh;
struct iscsi_uevent *ev;
uint32_t group;
+ int retries = ISCSI_SEND_MAX_ALLOWED;
nlh = nlmsg_hdr(skb);
if (nlh->nlmsg_len < sizeof(*nlh) + sizeof(*ev) ||
@@ -3712,6 +3715,10 @@ iscsi_if_rx(struct sk_buff *skb)
break;
err = iscsi_if_send_reply(portid, nlh->nlmsg_type,
ev, sizeof(*ev));
+ if (err == -EAGAIN && --retries < 0) {
+ printk(KERN_WARNING "Send reply failed, error %d\n", err);
+ break;
+ }
} while (err < 0 && err != -ECONNREFUSED && err != -ESRCH);
skb_pull(skb, rlen);
}