From 389f239c53420802ad5085e51e88c37e2df5e003 Mon Sep 17 00:00:00 2001
From: Chris Mason <clm@fb.com>
Date: Mon, 21 Mar 2016 06:59:09 -0700
Subject: [PATCH] btrfs: make sure we stay inside the bvec during
__btrfs_lookup_bio_sums
Commit c40a3d38aff4e1c (Btrfs: Compute and look up csums based on
sectorsized blocks) changes around how we walk the bios while looking up
crcs. There's an inner loop that is jumping to the next bvec based on
sectors and before it derefs the next bvec, it needs to make sure we're
still in the bio.
In this case, the outer loop would have decided to stop moving forward
too, and the bvec deref is never actually used for anything. But
CONFIG_DEBUG_PAGEALLOC catches it because we're outside our bio.
Signed-off-by: Chris Mason <clm@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/file-item.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 763fd170ff165..b5baf5bdc8e18 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -292,12 +292,22 @@ static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
page_bytes_left -= root->sectorsize;
if (!page_bytes_left) {
bio_index++;
+ /*
+ * make sure we're still inside the
+ * bio before we update page_bytes_left
+ */
+ if (bio_index >= bio->bi_vcnt) {
+ WARN_ON_ONCE(count);
+ goto done;
+ }
bvec++;
page_bytes_left = bvec->bv_len;
}
}
}
+
+done:
btrfs_free_path(path);
return 0;
}
--
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