This is a note to let you know that I've just added the patch titled btrfs: replace strncpy() with strscpy() to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: btrfs-replace-strncpy-with-strscpy.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 3bcbb61c068f6af9baf904e4d990208c58ae69f1 Author: Sasha Levin <sashal@xxxxxxxxxx> Date: Wed Jan 4 11:14:45 2023 -0500 btrfs: replace strncpy() with strscpy() [ Upstream commit 63d5429f68a3d4c4aa27e65a05196c17f86c41d6 ] Using strncpy() on NUL-terminated strings are deprecated. To avoid possible forming of non-terminated string strscpy() should be used. Found by Linux Verification Center (linuxtesting.org) with SVACE. CC: stable@xxxxxxxxxxxxxxx # 4.9+ Signed-off-by: Artem Chernyshev <artem.chernyshev@xxxxxxxxxxx> Reviewed-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 8553bd4361dd..64b443aa61ca 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -3299,13 +3299,10 @@ static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info, di_args->bytes_used = btrfs_device_get_bytes_used(dev); di_args->total_bytes = btrfs_device_get_total_bytes(dev); memcpy(di_args->uuid, dev->uuid, sizeof(di_args->uuid)); - if (dev->name) { - strncpy(di_args->path, rcu_str_deref(dev->name), - sizeof(di_args->path) - 1); - di_args->path[sizeof(di_args->path) - 1] = 0; - } else { + if (dev->name) + strscpy(di_args->path, rcu_str_deref(dev->name), sizeof(di_args->path)); + else di_args->path[0] = '\0'; - } out: rcu_read_unlock(); diff --git a/fs/btrfs/rcu-string.h b/fs/btrfs/rcu-string.h index a97dc74a4d3d..02f15321cecc 100644 --- a/fs/btrfs/rcu-string.h +++ b/fs/btrfs/rcu-string.h @@ -18,7 +18,11 @@ static inline struct rcu_string *rcu_string_strdup(const char *src, gfp_t mask) (len * sizeof(char)), mask); if (!ret) return ret; - strncpy(ret->str, src, len); + /* Warn if the source got unexpectedly truncated. */ + if (WARN_ON(strscpy(ret->str, src, len) < 0)) { + kfree(ret); + return NULL; + } return ret; }