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; };