[PATCH 6.1 065/473] nvmet: prevent sprintf() overflow in nvmet_subsys_nsid_exists()

Greg Kroah-Hartman
2024-06-06T14:13:11Z

From: Dan Carpenter <dan.carpenter@linaro.org>

[ Upstream commit d15dcd0f1a4753b57e66c64c8dc2a9779ff96aab ]

The nsid value is a u32 that comes from nvmet_req_find_ns(). It's
endian data and we're on an error path and both of those raise red
flags. So let's make this safer.

1) Make the buffer large enough for any u32.
2) Remove the unnecessary initialization.
3) Use snprintf() instead of sprintf() for even more safety.
4) The sprintf() function returns the number of bytes printed, not
counting the NUL terminator. It is impossible for the return value to
be <= 0 so delete that.

Fixes: 505363957fad ("nvmet: fix nvme status code when namespace is disabled")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/nvme/target/configfs.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index b1f5fa45bb4ac..40c1c3db5d7cd 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -618,10 +618,9 @@ static struct configfs_attribute *nvmet_ns_attrs[] = {
bool nvmet_subsys_nsid_exists(struct nvmet_subsys *subsys, u32 nsid)
{
struct config_item *ns_item;
- char name[4] = {};
+ char name[12];

- if (sprintf(name, "%u", nsid) <= 0)
- return false;
+ snprintf(name, sizeof(name), "%u", nsid);
mutex_lock(&subsys->namespaces_group.cg_subsys->su_mutex);
ns_item = config_group_find_item(&subsys->namespaces_group, name);
mutex_unlock(&subsys->namespaces_group.cg_subsys->su_mutex);
--
2.43.0