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Btrfs: fix use after free when close_ctree frees the orphan_rsv

PATCH Superseded Chris Mason 1 participant 2 messages Apr 7, 2015 Btrfs file system

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Chris Mason

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PATCH 1/1 Btrfs: fix use after free when close_ctree frees the orphan_rsv

Near the end of close_ctree, we're calling btrfs_free_block_rsv to free up the orphan rsv. The problem is this call updates the space_info, which has already been freed.

This adds a new __ function that directly calls kfree instead of trying to update the space infos.

Signed-off-by Chris Mason <[email protected]>
---
 fs/btrfs/ctree.h   | 1 +
 fs/btrfs/disk-io.c | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)
fs/btrfs/ctree.h +1 -0
index e1800d4..21032ed 100644
@@ -3488,6 +3488,7 @@ struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_root *root,
 					      unsigned short type);
 void btrfs_free_block_rsv(struct btrfs_root *root,
 			  struct btrfs_block_rsv *rsv);
+void __btrfs_free_block_rsv(struct btrfs_block_rsv *rsv);
 int btrfs_block_rsv_add(struct btrfs_root *root,
 			struct btrfs_block_rsv *block_rsv, u64 num_bytes,
 			enum btrfs_reserve_flush_enum flush);
fs/btrfs/disk-io.c +1 -1
index bb589b5..a123626 100644
@@ -3746,7 +3746,7 @@ void close_ctree(struct btrfs_root *root)
 
 	btrfs_free_stripe_hash_table(fs_info);
 
-	btrfs_free_block_rsv(root, root->orphan_block_rsv);
+	__btrfs_free_block_rsv(root->orphan_block_rsv);
 	root->orphan_block_rsv = NULL;
 
 	lock_chunks(root);
Signature · 1 line
1.8.1
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#1 lore raw

PATCH v2 1/1 Btrfs: fix use after free when close_ctree frees the orphan_rsv

Quoted 1 line

From 471717f48f9d853a6ced290d91e8b7f1d1c039da Mon Sep 17 00:00:00 2001

From: Chris Mason <[email protected]>
Date: Mon, 6 Apr 2015 18:17:00 -0700
Subject: [PATCH] Btrfs: fix use after free when close_ctree frees the
orphan_rsv

Near the end of close_ctree, we're calling btrfs_free_block_rsv to free up the orphan rsv. The problem is this call updates the space_info, which has already been freed.

This adds a new __ function that directly calls kfree instead of trying to update the space infos.

Signed-off-by Chris Mason <[email protected]>

---

v1 -> v2: whoops, get __btrfs-free_block_rsv in the right commit

 fs/btrfs/ctree.h       | 1 +
 fs/btrfs/disk-io.c     | 2 +-
 fs/btrfs/extent-tree.c | 7 +++++++
 3 files changed, 9 insertions(+), 1 deletion(-)
fs/btrfs/ctree.h +1 -0
index e1800d4..21032ed 100644
@@ -3488,6 +3488,7 @@ struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_root *root,
 					      unsigned short type);
 void btrfs_free_block_rsv(struct btrfs_root *root,
 			  struct btrfs_block_rsv *rsv);
+void __btrfs_free_block_rsv(struct btrfs_block_rsv *rsv);
 int btrfs_block_rsv_add(struct btrfs_root *root,
 			struct btrfs_block_rsv *block_rsv, u64 num_bytes,
 			enum btrfs_reserve_flush_enum flush);
fs/btrfs/disk-io.c +1 -1
index bb589b5..a123626 100644
@@ -3746,7 +3746,7 @@ void close_ctree(struct btrfs_root *root)
 
 	btrfs_free_stripe_hash_table(fs_info);
 
-	btrfs_free_block_rsv(root, root->orphan_block_rsv);
+	__btrfs_free_block_rsv(root->orphan_block_rsv);
 	root->orphan_block_rsv = NULL;
 
 	lock_chunks(root);
fs/btrfs/extent-tree.c +7 -0
index 9a53afc..0f1be4a 100644
@@ -4925,6 +4925,13 @@ void btrfs_free_block_rsv(struct btrfs_root *root,
 	kfree(rsv);
 }
 
+void __btrfs_free_block_rsv(struct btrfs_block_rsv *rsv)
+{
+	if (!rsv)
+		return;
+	kfree(rsv);
+}
+
 int btrfs_block_rsv_add(struct btrfs_root *root,
 			struct btrfs_block_rsv *block_rsv, u64 num_bytes,
 			enum btrfs_reserve_flush_enum flush)
Signature · 1 line
1.8.1