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authorFilipe Manana <fdmanana@gmail.com>2014-04-09 15:38:34 +0200
committerChris Mason <clm@fb.com>2014-06-10 02:20:44 +0200
commit35045bf2fd7c030f2583dbd80a2015f427778bf1 (patch)
tree22a4244b8da4ed5a9c569a381ca7887d96934649 /Documentation/backlight
parentBtrfs: make sure there are not any read requests before stopping workers (diff)
downloadlinux-35045bf2fd7c030f2583dbd80a2015f427778bf1.tar.xz
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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>
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