linux-kernel - [PATCH 5.9 234/391] btrfs: tree-checker: validate number of chunk stripes and parity

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Date:   Tue,  3 Nov 2020 21:34:45 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Qu Wenruo <wqu@...e.com>,
        Daniel Xu <dxu@...uu.xyz>, David Sterba <dsterba@...e.com>
Subject: [PATCH 5.9 234/391] btrfs: tree-checker: validate number of chunk stripes and parity

From: Daniel Xu <dxu@...uu.xyz>

commit 85d07fbe09efd1c529ff3e025e2f0d2c6c96a1b7 upstream.

If there's no parity and num_stripes < ncopies, a crafted image can
trigger a division by zero in calc_stripe_length().

The image was generated through fuzzing.

CC: stable@...r.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@...e.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=209587
Signed-off-by: Daniel Xu <dxu@...uu.xyz>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/btrfs/tree-checker.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -760,18 +760,36 @@ int btrfs_check_chunk_valid(struct exten
 	u64 type;
 	u64 features;
 	bool mixed = false;
+	int raid_index;
+	int nparity;
+	int ncopies;
 
 	length = btrfs_chunk_length(leaf, chunk);
 	stripe_len = btrfs_chunk_stripe_len(leaf, chunk);
 	num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
 	sub_stripes = btrfs_chunk_sub_stripes(leaf, chunk);
 	type = btrfs_chunk_type(leaf, chunk);
+	raid_index = btrfs_bg_flags_to_raid_index(type);
+	ncopies = btrfs_raid_array[raid_index].ncopies;
+	nparity = btrfs_raid_array[raid_index].nparity;
 
 	if (!num_stripes) {
 		chunk_err(leaf, chunk, logical,
 			  "invalid chunk num_stripes, have %u", num_stripes);
 		return -EUCLEAN;
 	}
+	if (num_stripes < ncopies) {
+		chunk_err(leaf, chunk, logical,
+			  "invalid chunk num_stripes < ncopies, have %u < %d",
+			  num_stripes, ncopies);
+		return -EUCLEAN;
+	}
+	if (nparity && num_stripes == nparity) {
+		chunk_err(leaf, chunk, logical,
+			  "invalid chunk num_stripes == nparity, have %u == %d",
+			  num_stripes, nparity);
+		return -EUCLEAN;
+	}
 	if (!IS_ALIGNED(logical, fs_info->sectorsize)) {
 		chunk_err(leaf, chunk, logical,
 		"invalid chunk logical, have %llu should aligned to %u",