| Message ID | 20220124170411.58169-1-zhou1615@umn.edu (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | media: bttv: Fix a NULL pointer dereference in bttv_s_fbuf() | expand |
On Tue, Jan 25, 2022 at 01:04:09AM +0800, Zhou Qingyang wrote: > In bttv_s_fbuf(), the return value of videobuf_sg_alloc() is assigned > to variable new and there is a dereference of it after that. the return > value of videobuf_sg_alloc() could be NULL on failure of allocation, > which could lead to a NULL pointer dereference. > > Fix this bug by adding a NULL check of new. > > This bug was found by a static analyzer. > > Builds with 'make allyesconfig' show no new warnings, > and our static analyzer no longer warns about this code > > Fixes: 402aa76aa5e5 ("V4L/DVB (6911): Converted bttv to use video_ioctl2") > Signed-off-by: Zhou Qingyang <zhou1615@umn.edu> > --- > 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. > > drivers/media/pci/bt8xx/bttv-driver.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/media/pci/bt8xx/bttv-driver.c b/drivers/media/pci/bt8xx/bttv-driver.c > index 5aa46593ddc6..c0664cffb881 100644 > --- a/drivers/media/pci/bt8xx/bttv-driver.c > +++ b/drivers/media/pci/bt8xx/bttv-driver.c > @@ -2627,6 +2627,8 @@ static int bttv_s_fbuf(struct file *file, void *f, > struct bttv_buffer *new; > > new = videobuf_sg_alloc(sizeof(*new)); > + if (!new) > + return -ENOMEM; > new->crop = btv->crop[!!fh->do_crop].rect; > bttv_overlay_risc(btv, &fh->ov, fh->ovfmt, new); > retval = bttv_switch_overlay(btv, fh, new); > -- > 2.25.1 > As stated before, umn.edu is still not allowed to contribute to the Linux kernel. Please work with your administration to resolve this issue.
diff --git a/drivers/media/pci/bt8xx/bttv-driver.c b/drivers/media/pci/bt8xx/bttv-driver.c index 5aa46593ddc6..c0664cffb881 100644 --- a/drivers/media/pci/bt8xx/bttv-driver.c +++ b/drivers/media/pci/bt8xx/bttv-driver.c @@ -2627,6 +2627,8 @@ static int bttv_s_fbuf(struct file *file, void *f, struct bttv_buffer *new; new = videobuf_sg_alloc(sizeof(*new)); + if (!new) + return -ENOMEM; new->crop = btv->crop[!!fh->do_crop].rect; bttv_overlay_risc(btv, &fh->ov, fh->ovfmt, new); retval = bttv_switch_overlay(btv, fh, new);
In bttv_s_fbuf(), the return value of videobuf_sg_alloc() is assigned to variable new and there is a dereference of it after that. the return value of videobuf_sg_alloc() could be NULL on failure of allocation, which could lead to a NULL pointer dereference. Fix this bug by adding a NULL check of new. This bug was found by a static analyzer. Builds with 'make allyesconfig' show no new warnings, and our static analyzer no longer warns about this code Fixes: 402aa76aa5e5 ("V4L/DVB (6911): Converted bttv to use video_ioctl2") Signed-off-by: Zhou Qingyang <zhou1615@umn.edu> --- 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. drivers/media/pci/bt8xx/bttv-driver.c | 2 ++ 1 file changed, 2 insertions(+)