[PATCH 5.10 39/80] net/smc: Use a mutex for locking "struct smc_pnettable"

Greg Kroah-Hartman
2022-02-28T17:44:25Z

From: Fabio M. De Francesco <fmdefrancesco@gmail.com>

commit 7ff57e98fb78ad94edafbdc7435f2d745e9e6bb5 upstream.

smc_pnetid_by_table_ib() uses read_lock() and then it calls smc_pnet_apply_ib()
which, in turn, calls mutex_lock(&smc_ib_devices.mutex).

read_lock() disables preemption. Therefore, the code acquires a mutex while in
atomic context and it leads to a SAC bug.

Fix this bug by replacing the rwlock with a mutex.

Reported-and-tested-by: syzbot+4f322a6d84e991c38775@syzkaller.appspotmail.com
Fixes: 64e28b52c7a6 ("net/smc: add pnet table namespace support")
Confirmed-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Link: https://lore.kernel.org/r/20220223100252.22562-1-fmdefrancesco@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/smc/smc_pnet.c | 42 +++++++++++++++++++++---------------------
net/smc/smc_pnet.h | 2 +-
2 files changed, 22 insertions(+), 22 deletions(-)

--- a/net/smc/smc_pnet.c
+++ b/net/smc/smc_pnet.c
@@ -112,7 +112,7 @@ static int smc_pnet_remove_by_pnetid(str
pnettable = &sn->pnettable;

/* remove table entry */
- write_lock(&pnettable->lock);
+ mutex_lock(&pnettable->lock);
list_for_each_entry_safe(pnetelem, tmp_pe, &pnettable->pnetlist,
list) {
if (!pnet_name ||
@@ -130,7 +130,7 @@ static int smc_pnet_remove_by_pnetid(str
rc = 0;
}
}
- write_unlock(&pnettable->lock);
+ mutex_unlock(&pnettable->lock);

/* if this is not the initial namespace, stop here */
if (net != &init_net)
@@ -191,7 +191,7 @@ static int smc_pnet_add_by_ndev(struct n
sn = net_generic(net, smc_net_id);
pnettable = &sn->pnettable;

- write_lock(&pnettable->lock);
+ mutex_lock(&pnettable->lock);
list_for_each_entry_safe(pnetelem, tmp_pe, &pnettable->pnetlist, list) {
if (pnetelem->type == SMC_PNET_ETH && !pnetelem->ndev &&
!strncmp(pnetelem->eth_name, ndev->name, IFNAMSIZ)) {
@@ -205,7 +205,7 @@ static int smc_pnet_add_by_ndev(struct n
break;
}
}
- write_unlock(&pnettable->lock);
+ mutex_unlock(&pnettable->lock);
return rc;
}

@@ -223,7 +223,7 @@ static int smc_pnet_remove_by_ndev(struc
sn = net_generic(net, smc_net_id);
pnettable = &sn->pnettable;

- write_lock(&pnettable->lock);
+ mutex_lock(&pnettable->lock);
list_for_each_entry_safe(pnetelem, tmp_pe, &pnettable->pnetlist, list) {
if (pnetelem->type == SMC_PNET_ETH && pnetelem->ndev == ndev) {
dev_put(pnetelem->ndev);
@@ -236,7 +236,7 @@ static int smc_pnet_remove_by_ndev(struc
break;
}
}
- write_unlock(&pnettable->lock);
+ mutex_unlock(&pnettable->lock);
return rc;
}

@@ -371,7 +371,7 @@ static int smc_pnet_add_eth(struct smc_p

rc = -EEXIST;
new_netdev = true;
- write_lock(&pnettable->lock);
+ mutex_lock(&pnettable->lock);
list_for_each_entry(tmp_pe, &pnettable->pnetlist, list) {
if (tmp_pe->type == SMC_PNET_ETH &&
!strncmp(tmp_pe->eth_name, eth_name, IFNAMSIZ)) {
@@ -381,9 +381,9 @@ static int smc_pnet_add_eth(struct smc_p
}
if (new_netdev) {
list_add_tail(&new_pe->list, &pnettable->pnetlist);
- write_unlock(&pnettable->lock);
+ mutex_unlock(&pnettable->lock);
} else {
- write_unlock(&pnettable->lock);
+ mutex_unlock(&pnettable->lock);
kfree(new_pe);
goto out_put;
}
@@ -445,7 +445,7 @@ static int smc_pnet_add_ib(struct smc_pn
new_pe->ib_port = ib_port;

new_ibdev = true;
- write_lock(&pnettable->lock);
+ mutex_lock(&pnettable->lock);
list_for_each_entry(tmp_pe, &pnettable->pnetlist, list) {
if (tmp_pe->type == SMC_PNET_IB &&
!strncmp(tmp_pe->ib_name, ib_name, IB_DEVICE_NAME_MAX)) {
@@ -455,9 +455,9 @@ static int smc_pnet_add_ib(struct smc_pn
}
if (new_ibdev) {
list_add_tail(&new_pe->list, &pnettable->pnetlist);
- write_unlock(&pnettable->lock);
+ mutex_unlock(&pnettable->lock);
} else {
- write_unlock(&pnettable->lock);
+ mutex_unlock(&pnettable->lock);
kfree(new_pe);
}
return (new_ibdev) ? 0 : -EEXIST;
@@ -602,7 +602,7 @@ static int _smc_pnet_dump(struct net *ne
pnettable = &sn->pnettable;

/* dump pnettable entries */
- read_lock(&pnettable->lock);
+ mutex_lock(&pnettable->lock);
list_for_each_entry(pnetelem, &pnettable->pnetlist, list) {
if (pnetid && !smc_pnet_match(pnetelem->pnet_name, pnetid))
continue;
@@ -617,7 +617,7 @@ static int _smc_pnet_dump(struct net *ne
break;
}
}
- read_unlock(&pnettable->lock);
+ mutex_unlock(&pnettable->lock);
return idx;
}

@@ -859,7 +859,7 @@ int smc_pnet_net_init(struct net *net)
struct smc_pnetids_ndev *pnetids_ndev = &sn->pnetids_ndev;

INIT_LIST_HEAD(&pnettable->pnetlist);
- rwlock_init(&pnettable->lock);
+ mutex_init(&pnettable->lock);
INIT_LIST_HEAD(&pnetids_ndev->list);
rwlock_init(&pnetids_ndev->lock);

@@ -939,7 +939,7 @@ static int smc_pnet_find_ndev_pnetid_by_
sn = net_generic(net, smc_net_id);
pnettable = &sn->pnettable;

- read_lock(&pnettable->lock);
+ mutex_lock(&pnettable->lock);
list_for_each_entry(pnetelem, &pnettable->pnetlist, list) {
if (pnetelem->type == SMC_PNET_ETH && ndev == pnetelem->ndev) {
/* get pnetid of netdev device */
@@ -948,7 +948,7 @@ static int smc_pnet_find_ndev_pnetid_by_
break;
}
}
- read_unlock(&pnettable->lock);
+ mutex_unlock(&pnettable->lock);
return rc;
}

@@ -1129,7 +1129,7 @@ int smc_pnetid_by_table_ib(struct smc_ib
sn = net_generic(&init_net, smc_net_id);
pnettable = &sn->pnettable;

- read_lock(&pnettable->lock);
+ mutex_lock(&pnettable->lock);
list_for_each_entry(tmp_pe, &pnettable->pnetlist, list) {
if (tmp_pe->type == SMC_PNET_IB &&
!strncmp(tmp_pe->ib_name, ib_name, IB_DEVICE_NAME_MAX) &&
@@ -1139,7 +1139,7 @@ int smc_pnetid_by_table_ib(struct smc_ib
break;
}
}
- read_unlock(&pnettable->lock);
+ mutex_unlock(&pnettable->lock);

return rc;
}
@@ -1158,7 +1158,7 @@ int smc_pnetid_by_table_smcd(struct smcd
sn = net_generic(&init_net, smc_net_id);
pnettable = &sn->pnettable;

- read_lock(&pnettable->lock);
+ mutex_lock(&pnettable->lock);
list_for_each_entry(tmp_pe, &pnettable->pnetlist, list) {
if (tmp_pe->type == SMC_PNET_IB &&
!strncmp(tmp_pe->ib_name, ib_name, IB_DEVICE_NAME_MAX)) {
@@ -1167,7 +1167,7 @@ int smc_pnetid_by_table_smcd(struct smcd
break;
}
}
- read_unlock(&pnettable->lock);
+ mutex_unlock(&pnettable->lock);

return rc;
}
--- a/net/smc/smc_pnet.h
+++ b/net/smc/smc_pnet.h
@@ -29,7 +29,7 @@ struct smc_link_group;
* @pnetlist: List of PNETIDs
*/
struct smc_pnettable {
- rwlock_t lock;
+ struct mutex lock;
struct list_head pnetlist;
};