[PATCH] nvme: Enter string size calculation “subsysnqn”

Denis Arefev
2024-12-26T10:46:01Z

When memory is allocated, the size of the string
is calculated nvmet_subsys_alloc(...).
When memory was accessed, constant size was used.

Fixes: 95409e277d83 ("nvmet: implement unique discovery NQN")
Reported-by: syzbot+a84181c81389771eb46a@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=a84181c81389771eb46a
Signed-off-by: Denis Arefev <arefev@swemel.ru>
---
drivers/nvme/target/configfs.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index eeee9e9b854c..2f74204d000e 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -2247,14 +2247,15 @@ static struct config_group nvmet_hosts_group;
static ssize_t nvmet_root_discovery_nqn_show(struct config_item *item,
char *page)
{
- return snprintf(page, PAGE_SIZE, "%s\n", nvmet_disc_subsys->subsysnqn);
+ return snprintf(page, strnlen(nvmet_disc_subsys->subsysnqn, PAGE_SIZE),
+ "%s\n", nvmet_disc_subsys->subsysnqn);
}

static ssize_t nvmet_root_discovery_nqn_store(struct config_item *item,
const char *page, size_t count)
{
struct list_head *entry;
- size_t len;
+ size_t len, nqn_len;

len = strcspn(page, "\n");
if (!len || len > NVMF_NQN_FIELD_LEN - 1)
@@ -2271,8 +2272,9 @@ static ssize_t nvmet_root_discovery_nqn_store(struct config_item *item,
return -EINVAL;
}
}
- memset(nvmet_disc_subsys->subsysnqn, 0, NVMF_NQN_FIELD_LEN);
- memcpy(nvmet_disc_subsys->subsysnqn, page, len);
+ nqn_len = strnlen(nvmet_disc_subsys->subsysnqn, NVMF_NQN_SIZE);
+ memset(nvmet_disc_subsys->subsysnqn, 0, nqn_len);
+ memcpy(nvmet_disc_subsys->subsysnqn, page, nqn_len);
up_write(&nvmet_config_sem);

return len;
--
2.43.0