| Message ID | 20200729221829.GA10623@embeddedor (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [next] ALSA: vmaster: Use flex_array_size() helper in memcpy() | expand |
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@kernel.org> > --- > 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. 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. 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); ? thanks, Takashi
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@kernel.org> >> --- >> 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
On Thu, 30 Jul 2020 15:12:33 +0200, Gustavo A. R. Silva wrote: > > > > 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@kernel.org> > >> --- > >> 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. OK, then I'll wait for the v2 for merging. > > 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 Ah, thanks, I didn't expect that the API change comes after rc1 into mainline. Then I can merge later the commits based on the late rc. Takashi
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)); srec->master = master_link; srec->flags = flags;
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@kernel.org> --- sound/core/vmaster.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)