| Message ID | 20211202160357.75173-1-zhou1615@umn.edu (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] media: meson: vdec: Fix a NULL pointer dereference in amvdec_add_ts() | expand |
On Fri, Dec 03, 2021 at 12:03:57AM +0800, Zhou Qingyang wrote: > In amvdec_add_ts(), there is a dereference of kzalloc(), which could lead > to a NULL pointer dereference on failure of kzalloc(). > > I fix this bug by adding a NULL check of new_ts. > > This bug was found by a static analyzer. The analysis employs > differential checking to identify inconsistent security operations > (e.g., checks or kfrees) between two code paths and confirms that the > inconsistent operations are not recovered in the current function or > the callers, so they constitute bugs. > > Note that, as a bug found by static analysis, it can be a false > positive or hard to trigger. Multiple researchers have cross-reviewed > the bug. > > Builds with CONFIG_VIDEO_MESON_VDEC=m show no new warnings, > and our static analyzer no longer warns about this code. > > Fixes: 876f123b8956 ("media: meson: vdec: bring up to compliance") > Signed-off-by: Zhou Qingyang <zhou1615@umn.edu> > --- ^^^ Thanks. Next time put the meta commentary about how the bug was found and the QC process under the the --- cut off line. We don't need to have that drama stored in the permanent git log. Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com> regards, dan carpenter
Em Fri, 3 Dec 2021 00:03:57 +0800 Zhou Qingyang <zhou1615@umn.edu> escreveu: > In amvdec_add_ts(), there is a dereference of kzalloc(), which could lead > to a NULL pointer dereference on failure of kzalloc(). > > I fix this bug by adding a NULL check of new_ts. > > This bug was found by a static analyzer. The analysis employs > differential checking to identify inconsistent security operations > (e.g., checks or kfrees) between two code paths and confirms that the > inconsistent operations are not recovered in the current function or > the callers, so they constitute bugs. > > Note that, as a bug found by static analysis, it can be a false > positive or hard to trigger. Multiple researchers have cross-reviewed > the bug. > > Builds with CONFIG_VIDEO_MESON_VDEC=m show no new warnings, > and our static analyzer no longer warns about this code. > > Fixes: 876f123b8956 ("media: meson: vdec: bring up to compliance") > Signed-off-by: Zhou Qingyang <zhou1615@umn.edu> > --- > Changes in v2: > - Delete dev_err() message > > drivers/staging/media/meson/vdec/vdec_helpers.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/staging/media/meson/vdec/vdec_helpers.c b/drivers/staging/media/meson/vdec/vdec_helpers.c > index b9125c295d1d..ac60514c475b 100644 > --- a/drivers/staging/media/meson/vdec/vdec_helpers.c > +++ b/drivers/staging/media/meson/vdec/vdec_helpers.c > @@ -234,6 +234,9 @@ void amvdec_add_ts(struct amvdec_session *sess, u64 ts, > unsigned long flags; > > new_ts = kzalloc(sizeof(*new_ts), GFP_KERNEL); > + if (!new_ts) > + return; > + > new_ts->ts = ts; > new_ts->tc = tc; > new_ts->offset = offset; I don't think this change is ok. Sure, it needs to check if kzalloc() fails, but it should return -ENOMEM and the caller should check if it returns an error. So, I would expect that this patch would also touch the caller function at drivers/staging/media/meson/vdec/esparser.c. Regards, Mauro Thanks, Mauro
On Tue, Dec 14, 2021 at 02:46:13PM +0100, Mauro Carvalho Chehab wrote: > Em Fri, 3 Dec 2021 00:03:57 +0800 > Zhou Qingyang <zhou1615@umn.edu> escreveu: > > > In amvdec_add_ts(), there is a dereference of kzalloc(), which could lead > > to a NULL pointer dereference on failure of kzalloc(). > > > > I fix this bug by adding a NULL check of new_ts. > > > > This bug was found by a static analyzer. The analysis employs > > differential checking to identify inconsistent security operations > > (e.g., checks or kfrees) between two code paths and confirms that the > > inconsistent operations are not recovered in the current function or > > the callers, so they constitute bugs. > > > > Note that, as a bug found by static analysis, it can be a false > > positive or hard to trigger. Multiple researchers have cross-reviewed > > the bug. > > > > Builds with CONFIG_VIDEO_MESON_VDEC=m show no new warnings, > > and our static analyzer no longer warns about this code. > > > > Fixes: 876f123b8956 ("media: meson: vdec: bring up to compliance") > > Signed-off-by: Zhou Qingyang <zhou1615@umn.edu> > > --- > > Changes in v2: > > - Delete dev_err() message > > > > drivers/staging/media/meson/vdec/vdec_helpers.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/staging/media/meson/vdec/vdec_helpers.c b/drivers/staging/media/meson/vdec/vdec_helpers.c > > index b9125c295d1d..ac60514c475b 100644 > > --- a/drivers/staging/media/meson/vdec/vdec_helpers.c > > +++ b/drivers/staging/media/meson/vdec/vdec_helpers.c > > @@ -234,6 +234,9 @@ void amvdec_add_ts(struct amvdec_session *sess, u64 ts, > > unsigned long flags; > > > > new_ts = kzalloc(sizeof(*new_ts), GFP_KERNEL); > > + if (!new_ts) > > + return; > > + > > new_ts->ts = ts; > > new_ts->tc = tc; > > new_ts->offset = offset; > > I don't think this change is ok. Sure, it needs to check if > kzalloc() fails, but it should return -ENOMEM and the caller > should check if it returns an error. So, I would expect > that this patch would also touch the caller function at > drivers/staging/media/meson/vdec/esparser.c. This is why umn.edu emails still are in my black-hole :(
diff --git a/drivers/staging/media/meson/vdec/vdec_helpers.c b/drivers/staging/media/meson/vdec/vdec_helpers.c index b9125c295d1d..ac60514c475b 100644 --- a/drivers/staging/media/meson/vdec/vdec_helpers.c +++ b/drivers/staging/media/meson/vdec/vdec_helpers.c @@ -234,6 +234,9 @@ void amvdec_add_ts(struct amvdec_session *sess, u64 ts, unsigned long flags; new_ts = kzalloc(sizeof(*new_ts), GFP_KERNEL); + if (!new_ts) + return; + new_ts->ts = ts; new_ts->tc = tc; new_ts->offset = offset;
In amvdec_add_ts(), there is a dereference of kzalloc(), which could lead to a NULL pointer dereference on failure of kzalloc(). I fix this bug by adding a NULL check of new_ts. This bug was found by a static analyzer. The analysis employs differential checking to identify inconsistent security operations (e.g., checks or kfrees) between two code paths and confirms that the inconsistent operations are not recovered in the current function or the callers, so they constitute bugs. Note that, as a bug found by static analysis, it can be a false positive or hard to trigger. Multiple researchers have cross-reviewed the bug. Builds with CONFIG_VIDEO_MESON_VDEC=m show no new warnings, and our static analyzer no longer warns about this code. Fixes: 876f123b8956 ("media: meson: vdec: bring up to compliance") Signed-off-by: Zhou Qingyang <zhou1615@umn.edu> --- Changes in v2: - Delete dev_err() message drivers/staging/media/meson/vdec/vdec_helpers.c | 3 +++ 1 file changed, 3 insertions(+)