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reiserfs: add check for an invalid ih_entry_count 

commit d24396c529 upstream.

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

Link: https://lore.kernel.org/r/20201101140958.3650143-1-rkovhaev@gmail.com
Reported-and-tested-by: syzbot+83b6f7cf9922cae5c4d7@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=83b6f7cf9922cae5c4d7
Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Rustam Kovhaev 2020-11-01 06:09:58 -08:00 committed by Greg Kroah-Hartman
parent 18e1101b0e
commit 01be033cc1
1 changed files with 6 additions and 0 deletions
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6
fs/reiserfs/stree.c
View File

@ -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);
}