Blame SOURCES/0446-fs-nilfs2-Reject-too-large-keys.patch

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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 16:49:09 +1100
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Subject: [PATCH] fs/nilfs2: Reject too-large keys
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NILFS2 has up to 7 keys, per the data structure. Do not permit array
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indices in excess of that.
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This catches some OOB reads. I don't know how controllable the invalidly
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read data is or if that could be used later in the program.
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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 | 7 ++++++-
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 1 file changed, 6 insertions(+), 1 deletion(-)
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diff --git a/grub-core/fs/nilfs2.c b/grub-core/fs/nilfs2.c
b71686
index 598a2a55b..61e8af9ff 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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@@ -569,6 +569,11 @@ grub_nilfs2_btree_lookup (struct grub_nilfs2_data *data,
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 static inline grub_uint64_t
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 grub_nilfs2_direct_lookup (struct grub_nilfs2_inode *inode, grub_uint64_t key)
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 {
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+  if (1 + key > 6)
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+    {
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+      grub_error (GRUB_ERR_BAD_FS, "key is too large");
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+      return 0xffffffffffffffff;
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+    }
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   return grub_le_to_cpu64 (inode->i_bmap[1 + key]);
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 }
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@@ -584,7 +589,7 @@ grub_nilfs2_bmap_lookup (struct grub_nilfs2_data *data,
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     {
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       grub_uint64_t ptr;
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       ptr = grub_nilfs2_direct_lookup (inode, key);
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-      if (need_translate)
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+      if (ptr != ((grub_uint64_t) 0xffffffffffffffff) && need_translate)
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 	ptr = grub_nilfs2_dat_translate (data, ptr);
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       return ptr;
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     }