This is a note to let you know that I've just added the patch titled ntfs: check overflow when iterating ATTR_RECORDs to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ntfs-check-overflow-when-iterating-attr_records.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 63095f4f3af59322bea984a6ae44337439348fe0 Mon Sep 17 00:00:00 2001 From: Hawkins Jiawei <yin31149@xxxxxxxxx> Date: Thu, 1 Sep 2022 00:09:38 +0800 Subject: ntfs: check overflow when iterating ATTR_RECORDs From: Hawkins Jiawei <yin31149@xxxxxxxxx> commit 63095f4f3af59322bea984a6ae44337439348fe0 upstream. Kernel 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 integer 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 some checks on calculating end address of current ATTR_RECORD during iteration. Link: https://lkml.kernel.org/r/20220831160935.3409-4-yin31149@xxxxxxxxx Link: https://lore.kernel.org/all/20220827105842.GM2030@kadam/ Signed-off-by: Hawkins Jiawei <yin31149@xxxxxxxxx> Suggested-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Cc: Anton Altaparmakov <anton@xxxxxxxxxx> Cc: chenxiaosong (A) <chenxiaosong2@xxxxxxxxxx> Cc: syzkaller-bugs <syzkaller-bugs@xxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ntfs/attrib.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/fs/ntfs/attrib.c +++ b/fs/ntfs/attrib.c @@ -617,6 +617,14 @@ static int ntfs_attr_find(const ATTR_TYP return -ENOENT; if (unlikely(!a->length)) break; + + /* check whether ATTR_RECORD's length wrap */ + if ((u8 *)a + le32_to_cpu(a->length) < (u8 *)a) + break; + /* check whether ATTR_RECORD's length is within bounds */ + if ((u8 *)a + le32_to_cpu(a->length) > mrec_end) + break; + if (a->type != type) continue; /* Patches currently in stable-queue which might be from yin31149@xxxxxxxxx are queue-5.4/ntfs-check-overflow-when-iterating-attr_records.patch queue-5.4/ntfs-fix-out-of-bounds-read-in-ntfs_attr_find.patch queue-5.4/ntfs-fix-use-after-free-in-ntfs_attr_find.patch