Messages in this thread | | | From | Linus Torvalds <> | Date | Sun, 5 Jun 2022 09:34:37 -0700 | Subject | Re: [PATCH] net/bluetooth: fix erroneous use of bitmap_from_u64() |
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On Sun, Jun 5, 2022 at 9:25 AM Yury Norov <yury.norov@gmail.com> wrote: > > The commit 0a97953fd221 ("lib: add bitmap_{from,to}_arr64") changed > implementation of bitmap_from_u64(), so that it doesn't typecast > argument to u64, and actually dereferences memory.
Gaah.
That code shouldn't use DECLARE_BITMAP() at all, it should just use
struct bdaddr_list_with_flags { .. unsigned long flags; };
and then use '&br_params->flags' when it nneds the actual atomic 'set_bit()' things and friends, and then when it copies the flags around it should just use 'flags' as an integer value.
The bitmap functions are literally defined to work as "bit N in a set of 'unsigned long'" exactly so that you can do that mixing of values and bit operations, and not have to worry about insane architectures that do big-endian bit ordering or things like that.
Using a 'bitmap' as if it's some bigger or potentially variable-sized thing for this kind of flags usage is crazy, when the code already does
/* Make sure number of flags doesn't exceed sizeof(current_flags) */ static_assert(__HCI_CONN_NUM_FLAGS < 32);
because other parts are limited to 32 bits.
I wonder how painful it would be to just fix that odd type mistake.
Linus
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