In btrfs_ref_tree_mod(), when !parent 're' was allocated
through kmalloc(). In the following code, if an error occurs,
the execution will be redirected to 'out' or 'out_unlock' and
the function will be exited. However, on some of the paths,
're' are not deallocated and may lead to memory leaks.

For example : lookup_block_entry() for 'be' returns null, the
out label will be invoked. During that flow ref and ra was
freed but not re, which can potentially lead to memleak

Reported-and-tested-by: syzbot+d66de4cbf532749df35f@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d66de4cbf532749df35f
Signed-off-by: Bragatheswaran Manickavel <bragathemanick0908@gmail.com>
---
V1 -> V2: 're' shouldn't be freed after it added to rbtree

 fs/btrfs/ref-verify.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/btrfs/ref-verify.c b/fs/btrfs/ref-verify.c
index 1f62976bee82..6486f0d7e993 100644
--- a/fs/btrfs/ref-verify.c
+++ b/fs/btrfs/ref-verify.c
@@ -794,6 +794,7 @@ int btrfs_ref_tree_mod(struct btrfs_fs_info *fs_info,
 			dump_ref_action(fs_info, ra);
 			kfree(ref);
 			kfree(ra);
+			kfree(re);
 			goto out_unlock;
 		} else if (be->num_refs == 0) {
 			btrfs_err(fs_info,
@@ -803,6 +804,7 @@ int btrfs_ref_tree_mod(struct btrfs_fs_info *fs_info,
 			dump_ref_action(fs_info, ra);
 			kfree(ref);
 			kfree(ra);
+			kfree(re);
 			goto out_unlock;
 		}
 
-- 
2.34.1

On Sat, Nov 18, 2023 at 02:40:12PM +0530, Bragatheswaran Manickavel wrote:
> In btrfs_ref_tree_mod(), when !parent 're' was allocated
> through kmalloc(). In the following code, if an error occurs,
> the execution will be redirected to 'out' or 'out_unlock' and
> the function will be exited. However, on some of the paths,
> 're' are not deallocated and may lead to memory leaks.
> 
> For example : lookup_block_entry() for 'be' returns null, the
> out label will be invoked. During that flow ref and ra was
> freed but not re, which can potentially lead to memleak
> 
> Reported-and-tested-by: syzbot+d66de4cbf532749df35f@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=d66de4cbf532749df35f
> Signed-off-by: Bragatheswaran Manickavel <bragathemanick0908@gmail.com>

Added to misc-next, thanks.