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grub2/SOURCES/0446-fs-nilfs2-Reject-too-l...

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Daniel Axtens <dja@axtens.net>
Date: Mon, 18 Jan 2021 16:49:09 +1100
Subject: [PATCH] fs/nilfs2: Reject too-large keys
NILFS2 has up to 7 keys, per the data structure. Do not permit array
indices in excess of that.
This catches some OOB reads. I don't know how controllable the invalidly
read data is or if that could be used later in the program.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
grub-core/fs/nilfs2.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/grub-core/fs/nilfs2.c b/grub-core/fs/nilfs2.c
index 598a2a55b..61e8af9ff 100644
--- a/grub-core/fs/nilfs2.c
+++ b/grub-core/fs/nilfs2.c
@@ -569,6 +569,11 @@ grub_nilfs2_btree_lookup (struct grub_nilfs2_data *data,
static inline grub_uint64_t
grub_nilfs2_direct_lookup (struct grub_nilfs2_inode *inode, grub_uint64_t key)
{
+ if (1 + key > 6)
+ {
+ grub_error (GRUB_ERR_BAD_FS, "key is too large");
+ return 0xffffffffffffffff;
+ }
return grub_le_to_cpu64 (inode->i_bmap[1 + key]);
}
@@ -584,7 +589,7 @@ grub_nilfs2_bmap_lookup (struct grub_nilfs2_data *data,
{
grub_uint64_t ptr;
ptr = grub_nilfs2_direct_lookup (inode, key);
- if (need_translate)
+ if (ptr != ((grub_uint64_t) 0xffffffffffffffff) && need_translate)
ptr = grub_nilfs2_dat_translate (data, ptr);
return ptr;
}