Commit 59f37036 authored by Filipe Manana's avatar Filipe Manana Committed by David Sterba
Browse files

btrfs: fix use-after-free on inode when scanning root during em shrinking 



At btrfs_scan_root() we are accessing the inode's root (and fs_info) in a
call to btrfs_fs_closing() after we have scheduled the inode for a delayed
iput, and that can result in a use-after-free on the inode in case the
cleaner kthread does the iput before we dereference the inode in the call
to btrfs_fs_closing().

Fix this by using the fs_info stored already in a local variable instead
of doing inode->root->fs_info.

Fixes: 10204438 ("btrfs: make the extent map shrinker run asynchronously as a work queue job")
CC: stable@vger.kernel.org # 6.13+
Tested-by: default avatarIvan Shapovalov <intelfx@intelfx.name>
Link: https://lore.kernel.org/linux-btrfs/0414d690ac5680d0d77dfc930606cdc36e42e12f.camel@intelfx.name/


Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 290237fd

fs/btrfs/extent_map.c

+1 −2
Original line number Diff line number Diff line
@@ -1222,8 +1222,7 @@ static long btrfs_scan_root(struct btrfs_root *root, struct btrfs_em_shrink_ctx 
		fs_info->em_shrinker_last_ino = btrfs_ino(inode);

		btrfs_add_delayed_iput(inode);



		if (ctx->scanned >= ctx->nr_to_scan ||

		    btrfs_fs_closing(inode->root->fs_info))

		if (ctx->scanned >= ctx->nr_to_scan || btrfs_fs_closing(fs_info))

			break;



		cond_resched();