linux-kernel - [PATCH] btrfs: ref-verify: fix memory leaks

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Message-Id: <20231112165648.10537-1-bragathemanick0908@gmail.com>
Date:   Sun, 12 Nov 2023 22:26:48 +0530
From:   Bragatheswaran Manickavel <bragathemanick0908@...il.com>
To:     clm@...com, josef@...icpanda.com, dsterba@...e.com
Cc:     Bragatheswaran Manickavel <bragathemanick0908@...il.com>,
        linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzbot+d66de4cbf532749df35f@...kaller.appspotmail.com
Subject: [PATCH] btrfs: ref-verify: fix memory leaks

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@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d66de4cbf532749df35f
Signed-off-by: Bragatheswaran Manickavel <bragathemanick0908@...il.com>
---
 fs/btrfs/ref-verify.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/btrfs/ref-verify.c b/fs/btrfs/ref-verify.c
index 95d28497de7c..50b59b3dc474 100644
--- a/fs/btrfs/ref-verify.c
+++ b/fs/btrfs/ref-verify.c
@@ -791,6 +791,7 @@ 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,
@@ -800,6 +801,7 @@ 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;
 		}
 
@@ -822,6 +824,7 @@ 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;
 			}
 			exist->num_refs--;
@@ -838,6 +841,7 @@ 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;
 		}
 		kfree(ref);
@@ -849,6 +853,7 @@ 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