2020-11-01 14:14:07

by Rustam Kovhaev

Subject: [PATCH] reiserfs: add check for an invalid ih_entry_count

when directory item has an invalid value set for ih_entry_count it might
trigger use-after-free or out-of-bounds read in bin_search_in_dir_item()

ih_entry_count * IH_SIZE for directory item should not be larger than
ih_item_len

Reported-and-tested-by: [email protected]
Link: https://syzkaller.appspot.com/bug?extid=83b6f7cf9922cae5c4d7
Signed-off-by: Rustam Kovhaev <[email protected]>
---
fs/reiserfs/stree.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/fs/reiserfs/stree.c b/fs/reiserfs/stree.c
index 8bf88d690729..476a7ff49482 100644
--- a/fs/reiserfs/stree.c
+++ b/fs/reiserfs/stree.c
@@ -454,6 +454,12 @@ static int is_leaf(char *buf, int blocksize, struct buffer_head *bh)
"(second one): %h", ih);
return 0;
}
+ if (is_direntry_le_ih(ih) && (ih_item_len(ih) < (ih_entry_count(ih) * IH_SIZE))) {
+ reiserfs_warning(NULL, "reiserfs-5093",
+ "item entry count seems wrong %h",
+ ih);
+ return 0;
+ }
prev_location = ih_location(ih);
}

--
2.28.0

2020-11-26 16:01:39

by Jan Kara

Subject: Re: [PATCH] reiserfs: add check for an invalid ih_entry_count

On Sun 01-11-20 06:09:58, Rustam Kovhaev wrote:
> when directory item has an invalid value set for ih_entry_count it might
> trigger use-after-free or out-of-bounds read in bin_search_in_dir_item()
>
> ih_entry_count * IH_SIZE for directory item should not be larger than
> ih_item_len
>
> Reported-and-tested-by: [email protected]
> Link: https://syzkaller.appspot.com/bug?extid=83b6f7cf9922cae5c4d7
> Signed-off-by: Rustam Kovhaev <[email protected]>

Thanks! I've added the patch to my tree and will push it to Linus.

Honza

> ---
> fs/reiserfs/stree.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/fs/reiserfs/stree.c b/fs/reiserfs/stree.c
> index 8bf88d690729..476a7ff49482 100644
> --- a/fs/reiserfs/stree.c
> +++ b/fs/reiserfs/stree.c
> @@ -454,6 +454,12 @@ static int is_leaf(char *buf, int blocksize, struct buffer_head *bh)
> "(second one): %h", ih);
> return 0;
> }
> + if (is_direntry_le_ih(ih) && (ih_item_len(ih) < (ih_entry_count(ih) * IH_SIZE))) {
> + reiserfs_warning(NULL, "reiserfs-5093",
> + "item entry count seems wrong %h",
> + ih);
> + return 0;
> + }
> prev_location = ih_location(ih);
> }
>
> --
> 2.28.0
>
--
Jan Kara <[email protected]>
SUSE Labs, CR