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From: chenxiaosong (A) <che...@hu...> - 2022-08-27 01:29:04
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在 2022/8/26 20:27, Hawkins Jiawei 写道: > syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > > Looks like it is improper check order that causes this bug. > > Signed-off-by: Hawkins Jiawei <yin...@gm...> > --- > fs/ntfs/attrib.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c > index 52615e6090e1..6480cd2d371d 100644 > --- a/fs/ntfs/attrib.c > +++ b/fs/ntfs/attrib.c > @@ -594,10 +594,11 @@ static int ntfs_attr_find(const ATTR_TYPE type, const ntfschar *name, > for (;; a = (ATTR_RECORD*)((u8*)a + le32_to_cpu(a->length))) { > u8 *mrec_end = (u8 *)ctx->mrec + > le32_to_cpu(ctx->mrec->bytes_allocated); > + if ((u8*)a < (u8*)ctx->mrec || (u8*)a > mrec_end) > + break; > u8 *name_end = (u8 *)a + le16_to_cpu(a->name_offset) + > a->name_length * sizeof(ntfschar); > - if ((u8*)a < (u8*)ctx->mrec || (u8*)a > mrec_end || > - name_end > mrec_end) > + if (name_end > mrec_end) > break; > ctx->attr = a; > if (unlikely(le32_to_cpu(a->type) > le32_to_cpu(type) || > The reason is that a->length is 0, it will occur uaf when deref any field of ATTR_RECORD. It seems that changing check order will not fix root cause, if the condition "if ((u8*)a < (u8*)ctx->mrec || (u8*)a > mrec_end)" is false, uaf will still occur. Do you have any thoughts on this ? |
