Re: [PATCH] btrfs: avoid using fixed char array size for tree names

[Josef Bacik <josef@toxicpanda.com>]

On Fri, Jul 19, 2024 at 02:20:39PM +0930, Qu Wenruo wrote:
> [BUG]
> There is a bug report that using the latest trunk GCC, btrfs would cause
> unterminated-string-initialization warning:
> 
>   linux-6.6/fs/btrfs/print-tree.c:29:49: error: initializer-string for array of ‘char’ is too long [-Werror=unterminated-string-initialization]
>    29 |         { BTRFS_BLOCK_GROUP_TREE_OBJECTID,      "BLOCK_GROUP_TREE"      },
>       |
>       ^~~~~~~~~~~~~~~~~~
> 
> [CAUSE]
> To print tree names we have an array of root_name_map structure, which
> uses "char name[16];" to store the name string of a tree.
> 
> But the following trees have names exactly at 16 chars length:
> - "BLOCK_GROUP_TREE"
> - "RAID_STRIPE_TREE"
> 
> This means we will have no space for the terminating '\0', and can lead
> to unexpected access when printing the name.
> 
> [FIX]
> Instead of "char name[16];" use "const char *" instead.
> 
> Since the name strings are all read-only data, and are all NULL
> terminated by default, there is not much need to bother the length at
> all.
> 
> Reported-by: Sam James <sam@gentoo.org>
> Signed-off-by: Qu Wenruo <wqu@suse.com>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef