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reiserfs: check directory items on read from disk

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While verifying the leaf item that we read from the disk, reiserfs
doesn't check the directory items, this could cause a crash when we
read a directory item from the disk that has an invalid deh_location.

This patch adds a check to the directory items read from the disk that
does a bounds check on deh_location for the directory entries. Any
directory entry header with a directory entry offset greater than the
item length is considered invalid.

Link: https://lore.kernel.org/r/20210709152929.766363-1-chouhan.shreyansh630@gmail.com
Reported-by: syzbot+c31a48e6702ccb3d64c9@syzkaller.appspotmail.com
Signed-off-by: Shreyansh Chouhan <chouhan.shreyansh630@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Shreyansh Chouhan 2021-07-09 20:59:29 +05:30 committed by Jan Kara
parent 728d392f8a
commit 13d257503c
1 changed files with 26 additions and 5 deletions
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31
fs/reiserfs/stree.c
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@ -387,6 +387,24 @@ void pathrelse(struct treepath *search_path)
search_path->path_length = ILLEGAL_PATH_ELEMENT_OFFSET;
}
static int has_valid_deh_location(struct buffer_head *bh, struct item_head *ih)
{
struct reiserfs_de_head *deh;
int i;
deh = B_I_DEH(bh, ih);
for (i = 0; i < ih_entry_count(ih); i++) {
if (deh_location(&deh[i]) > ih_item_len(ih)) {
reiserfs_warning(NULL, "reiserfs-5094",
"directory entry location seems wrong %h",
&deh[i]);
return 0;
}
}
return 1;
}
static int is_leaf(char *buf, int blocksize, struct buffer_head *bh)
{
struct block_head *blkh;
@ -454,11 +472,14 @@ 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;
if (is_direntry_le_ih(ih)) {
if (ih_item_len(ih) < (ih_entry_count(ih) * IH_SIZE)) {
reiserfs_warning(NULL, "reiserfs-5093",
"item entry count seems wrong %h",
ih);
return 0;
}
return has_valid_deh_location(bh, ih);
}
prev_location = ih_location(ih);
}