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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Daniel Axtens <dja@axtens.net>
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Date: Mon, 18 Jan 2021 16:49:44 +1100
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Subject: [PATCH] fs/nilfs2: Don't search children if provided number is too
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large
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NILFS2 reads the number of children a node has from the node. Unfortunately,
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that's not trustworthy. Check if it's beyond what the filesystem permits and
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reject it if so.
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This blocks some OOB reads. I'm not sure how controllable the read is and what
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could be done with invalidly read data later on.
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Signed-off-by: Daniel Axtens <dja@axtens.net>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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---
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grub-core/fs/nilfs2.c | 38 +++++++++++++++++++++++---------------
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1 file changed, 23 insertions(+), 15 deletions(-)
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diff --git a/grub-core/fs/nilfs2.c b/grub-core/fs/nilfs2.c
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index 61e8af9ff..054ad3dc1 100644
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--- a/grub-core/fs/nilfs2.c
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+++ b/grub-core/fs/nilfs2.c
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@@ -416,14 +416,34 @@ grub_nilfs2_btree_node_get_key (struct grub_nilfs2_btree_node *node,
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}
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static inline int
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-grub_nilfs2_btree_node_lookup (struct grub_nilfs2_btree_node *node,
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+grub_nilfs2_btree_node_nchildren_max (struct grub_nilfs2_data *data,
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+ struct grub_nilfs2_btree_node *node)
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+{
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+ int node_children_max = ((NILFS2_BLOCK_SIZE (data) -
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+ sizeof (struct grub_nilfs2_btree_node) -
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+ NILFS_BTREE_NODE_EXTRA_PAD_SIZE) /
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+ (sizeof (grub_uint64_t) + sizeof (grub_uint64_t)));
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+
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+ return (node->bn_flags & NILFS_BTREE_NODE_ROOT) ? 3 : node_children_max;
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+}
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+
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+static inline int
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+grub_nilfs2_btree_node_lookup (struct grub_nilfs2_data *data,
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+ struct grub_nilfs2_btree_node *node,
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grub_uint64_t key, int *indexp)
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{
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grub_uint64_t nkey;
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int index, low, high, s;
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low = 0;
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+
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high = grub_le_to_cpu16 (node->bn_nchildren) - 1;
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+ if (high >= grub_nilfs2_btree_node_nchildren_max (data, node))
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+ {
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+ grub_error (GRUB_ERR_BAD_FS, "too many children");
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+ return 0;
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+ }
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+
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index = 0;
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s = 0;
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while (low <= high)
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@@ -459,18 +479,6 @@ grub_nilfs2_btree_node_lookup (struct grub_nilfs2_btree_node *node,
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return s == 0;
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}
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-static inline int
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-grub_nilfs2_btree_node_nchildren_max (struct grub_nilfs2_data *data,
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- struct grub_nilfs2_btree_node *node)
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-{
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- int node_children_max = ((NILFS2_BLOCK_SIZE (data) -
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- sizeof (struct grub_nilfs2_btree_node) -
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- NILFS_BTREE_NODE_EXTRA_PAD_SIZE) /
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- (sizeof (grub_uint64_t) + sizeof (grub_uint64_t)));
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-
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- return (node->bn_flags & NILFS_BTREE_NODE_ROOT) ? 3 : node_children_max;
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-}
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-
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static inline grub_uint64_t *
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grub_nilfs2_btree_node_dptrs (struct grub_nilfs2_data *data,
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struct grub_nilfs2_btree_node *node)
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@@ -517,7 +525,7 @@ grub_nilfs2_btree_lookup (struct grub_nilfs2_data *data,
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node = grub_nilfs2_btree_get_root (inode);
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level = grub_nilfs2_btree_get_level (node);
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- found = grub_nilfs2_btree_node_lookup (node, key, &index);
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+ found = grub_nilfs2_btree_node_lookup (data, node, key, &index);
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ptr = grub_nilfs2_btree_node_get_ptr (data, node, index);
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if (need_translate)
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ptr = grub_nilfs2_dat_translate (data, ptr);
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@@ -538,7 +546,7 @@ grub_nilfs2_btree_lookup (struct grub_nilfs2_data *data,
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}
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if (!found)
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- found = grub_nilfs2_btree_node_lookup (node, key, &index);
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+ found = grub_nilfs2_btree_node_lookup (data, node, key, &index);
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else
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index = 0;
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