On 4/27/20 3:23 AM, Vladimir Sementsov-Ogievskiy wrote:
The function is called from 64bit io handlers, and bytes is just passed
to throttle_account() which is 64bit too (unsigned though). So, let's
convert intermediate argument to 64bit too.
My audit for this patch:
Caller has 32-bit, this patch now causes widening which is safe:
block/block-backend.c: blk_do_preadv() passes 'unsigned int'
block/block-backend.c: blk_do_pwritev_part() passes 'unsigned int'
block/throttle.c: throttle_co_pwrite_zeroes() passes 'int'
block/throttle.c: throttle_co_pdiscard() passes 'int'
Caller has 64-bit, this patch fixes potential bug where pre-patch could
narrow, except it's easy enough to trace that callers are still capped
at 2G actions:
block/throttle.c: throttle_co_preadv() passes 'uint64_t'
block/throttle.c: throttle_co_pwritev() passes 'uint64_t'
Implementation in question: block/throttle-groups.c
throttle_group_co_io_limits_intercept() takes 'unsigned int bytes' and
uses it:
argument to util/throttle.c throttle_account(uint64_t)
All safe: it patches a latent bug, and does not introduce any 64-bit
gotchas once throttle_co_p{read,write}v are relaxed, and assuming
throttle_account() is not buggy.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
---
include/block/throttle-groups.h | 2 +-
block/throttle-groups.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
Reviewed-by: Eric Blake <ebl...@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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