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Create a new string with kstrndup instead of using the old buffer. Reported-by: syzbot+ff4aab278fa7e27e0f9e@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3Dff4aab278fa7e27e0f9e Fixes: 95409e277d83 ("nvmet: implement unique discovery NQN") Signed-off-by: Leo Stone Reviewed-by: Christoph Hellwig Reviewed-by: Sagi Grimberg --- v3: Use kstrndup to avoid copying the newline, and free outside lock. v2: https://lore.kernel.org/all/20241218160458.9587-2-leocstone@gmail.com/ v1: https://lore.kernel.org/all/20241218005909.89092-2-leocstone@gmail.com/ --- drivers/nvme/target/configfs.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c index eeee9e9b854c..9c109b93ffbf 100644 --- a/drivers/nvme/target/configfs.c +++ b/drivers/nvme/target/configfs.c @@ -2254,12 +2254,17 @@ static ssize_t nvmet_root_discovery_nqn_store(struc= t config_item *item, const char *page, size_t count) { struct list_head *entry; + char *old_nqn, *new_nqn; size_t len; =20 len =3D strcspn(page, "\n"); if (!len || len > NVMF_NQN_FIELD_LEN - 1) return -EINVAL; =20 + new_nqn =3D kstrndup(page, len, GFP_KERNEL); + if (!new_nqn) + return -ENOMEM; + down_write(&nvmet_config_sem); list_for_each(entry, &nvmet_subsystems_group.cg_children) { struct config_item *item =3D @@ -2268,13 +2273,15 @@ static ssize_t nvmet_root_discovery_nqn_store(struc= t config_item *item, if (!strncmp(config_item_name(item), page, len)) { pr_err("duplicate NQN %s\n", config_item_name(item)); up_write(&nvmet_config_sem); + kfree(new_nqn); return -EINVAL; } } - memset(nvmet_disc_subsys->subsysnqn, 0, NVMF_NQN_FIELD_LEN); - memcpy(nvmet_disc_subsys->subsysnqn, page, len); + old_nqn =3D nvmet_disc_subsys->subsysnqn; + nvmet_disc_subsys->subsysnqn =3D new_nqn; up_write(&nvmet_config_sem); =20 + kfree(old_nqn); return len; } =20 --=20 2.43.0