Am 24.11.2023 um 15:05 hat Дмитрий Фролов geschrieben: > > > On 24.11.2023 16:06, Kevin Wolf wrote: > > Am 24.11.2023 um 12:30 hat Dmitry Frolov geschrieben: > > > blk_bs() may return NULL, which will be dereferenced without a check in > > > bdrv_commit(). > > > > > > Found by Linux Verification Center (linuxtesting.org) with SVACE. > > > > > > Signed-off-by: Dmitry Frolov <fro...@swemel.ru> > > Do you have a reproducer for a crash? > Actually, there was no crash. This problem was found by static analyzer. > > As far as I can see, it will not be dereferenced, because > > blk_is_available() returns false and we return an error before > > calling bdrv_commit(): > As I see, there are 2 reasons, why blk_bs() may return NULL: > blk->root == NULL or blk->root->bs == NULL
blk->root->bs == NULL shouldn't happen, but the code we're looking at is safe even for this case. > At the same time, blk_is_available() checks for > blk_co_is_inserted(blk) and blk_dev_is_tray_open(blk). > Does it also guarantee that blk->root and blk->root->bs are not NULL? > This is not really obvious. blk_co_is_inserted() does, it returns false for blk_bs(blk) == NULL. > Maybe, in this case, it makes sense to check blk->root before of > checking blk_is_available()? Checking blk->root and those few other things is a really common thing that most operations do, which is why we have blk_is_available() to check all of this. If we did the checks before calling it, we wouldn't need blk_is_available() any more. Kevin
