Messages in this thread Patch in this message | | | From | Hawkins Jiawei <> | Subject | [PATCH 3/3] ntfs: check overflow when iterates ATTR_RECORDs | Date | Wed, 31 Aug 2022 10:48:54 +0800 |
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Kernel will iterates over ATTR_RECORDs in mft record in ntfs_attr_find(). Because the ATTR_RECORDs are next to each other, kernel can get the next ATTR_RECORD from end address of current ATTR_RECORD, through current ATTR_RECORD length field.
The problem is that during iteration, when kernel calculates the end address of current ATTR_RECORD, kernel may trigger an overflow bug in executing `a = (ATTR_RECORD*)((u8*)a + le32_to_cpu(a->length))`. This may wrap, leading to a forever iteration on 32bit systems.
This patch solves it by adding an overflow checking on calculating end address of current ATTR_RECORD during iteration.
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com> Link: https://lore.kernel.org/all/20220827105842.GM2030@kadam/ Signed-off-by: Hawkins Jiawei <yin31149@gmail.com> --- fs/ntfs/attrib.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c index 904734e34507..55e618c9e63e 100644 --- a/fs/ntfs/attrib.c +++ b/fs/ntfs/attrib.c @@ -617,6 +617,9 @@ static int ntfs_attr_find(const ATTR_TYPE type, const ntfschar *name, return -ENOENT; if (unlikely(!a->length)) break; + /* check for wrap around */ + if ((u8 *)a + le32_to_cpu(a->length) < (u8 *)a) + break; if (a->type != type) continue; /* -- 2.25.1
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