On 7/30/20 03:41, Takashi Iwai wrote: > On Thu, 30 Jul 2020 00:18:29 +0200, > Gustavo A. R. Silva wrote: >> >> Make use of the flex_array_size() helper to calculate the size of a >> flexible array member within an enclosing structure. >> >> This helper offers defense-in-depth against potential integer overflows >> and makes it explicitly clear that we are dealing with a flexible array >> member. >> >> Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> >> --- >> sound/core/vmaster.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/sound/core/vmaster.c b/sound/core/vmaster.c >> index ab36f9898711..21ce4082cb5f 100644 >> --- a/sound/core/vmaster.c >> +++ b/sound/core/vmaster.c >> @@ -262,7 +262,8 @@ int _snd_ctl_add_follower(struct snd_kcontrol *master, >> return -ENOMEM; >> srec->kctl = follower; >> srec->follower = *follower; >> - memcpy(srec->follower.vd, follower->vd, follower->count * sizeof(*follower->vd)); >> + memcpy(srec->follower.vd, follower->vd, flex_array_size(srec, follower.vd, >> + srec->follower.count)); > > Changing from follower->count to srec->follower.count isn't obvious, > so it should have been mentioned in the log; other than that, the code > change looks good. > Yeah; you're right. I'll include that in the changelog text. > But since the API isn't in Linus tree yet, I'll postpone the merge > until the API reaches to upstream. Maybe I can merge this during RC1 > merge window, as those are trivial. > The API is already in mainline, see: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/overflow.h#n320 > > BTW, looking at those patterns, I wonder whether it'd make sense to > make the whole memset() call as a macro like > > safe_copy_array(srec->follower.vd, follower->vd, follower->count); > > ? > Yep; I was actually thinking about that, yesterday. I might implement it for the next development cycle. :) Thanks for the feedback. -- Gustavo
