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author | Filipe Manana <fdmanana@gmail.com> | 2014-04-09 14:38:34 +0100 |
---|---|---|
committer | Chris Mason <clm@fb.com> | 2014-06-09 17:20:44 -0700 |
commit | 35045bf2fd7c030f2583dbd80a2015f427778bf1 (patch) | |
tree | 22a4244b8da4ed5a9c569a381ca7887d96934649 /fs | |
parent | de348ee022175401e77d7662b7ca6e231a94e3fd (diff) | |
download | op-kernel-dev-35045bf2fd7c030f2583dbd80a2015f427778bf1.zip op-kernel-dev-35045bf2fd7c030f2583dbd80a2015f427778bf1.tar.gz |
Btrfs: don't access non-existent key when csum tree is empty
When the csum tree is empty, our leaf (path->nodes[0]) has a number
of items equal to 0 and since btrfs_header_nritems() returns an
unsigned integer (and so is our local nritems variable) the following
comparison always evaluates to false:
if (path->slots[0] >= nritems - 1) {
As the casting rules lead to:
if ((u32)0 >= (u32)4294967295) {
This makes us access key at slot paths->slots[0] + 1 (1) of the empty leaf
some lines below:
btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
found_key.type != BTRFS_EXTENT_CSUM_KEY) {
found_next = 1;
goto insert;
}
So just don't access such non-existent slot and don't set found_next to 1
when the tree is empty. It's very unlikely we'll get a random key with the
objectid and type values above, which is where we could go into trouble.
If nritems is 0, just set found_next to 1 anyway as it will make us insert
a csum item covering our whole extent (or the whole leaf) when the tree is
empty.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/btrfs/file-item.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c index 67751b7..609d56b 100644 --- a/fs/btrfs/file-item.c +++ b/fs/btrfs/file-item.c @@ -750,7 +750,7 @@ again: int slot = path->slots[0] + 1; /* we didn't find a csum item, insert one */ nritems = btrfs_header_nritems(path->nodes[0]); - if (path->slots[0] >= nritems - 1) { + if (!nritems || (path->slots[0] >= nritems - 1)) { ret = btrfs_next_leaf(root, path); if (ret == 1) found_next = 1; |