| Message ID | 20201220201124.13688-1-sakari.ailus@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,1/1] v4l: ioctl: Fix memory leak in video_usercopy | expand |
Sakari, On 12/21/20 4:11 AM, Sakari Ailus wrote: > When an IOCTL with argument size larger than 128 that also used array > arguments were handled, two memory allocations were made but alas, only > the latter one of them was released. This happened because there was only > a single local variable to hold such a temporary allocation. > > Fix this by adding separate variables to hold the pointers to the > temporary allocations. > > Reported-by: Arnd Bergmann <arnd@kernel.org> > Reported-by: syzbot+1115e79c8df6472c612b@syzkaller.appspotmail.com > Fixes: d14e6d76ebf7 ("[media] v4l: Add multi-planar ioctl handling code") > Cc: stable@vger.kernel.org > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> > Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > --- > drivers/media/v4l2-core/v4l2-ioctl.c | 32 ++++++++++++---------------- > 1 file changed, 14 insertions(+), 18 deletions(-) > > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c > index 3198abdd538c..9906b41004e9 100644 > --- a/drivers/media/v4l2-core/v4l2-ioctl.c > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c > @@ -3283,7 +3283,7 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg, > v4l2_kioctl func) > { > char sbuf[128]; > - void *mbuf = NULL; > + void *mbuf = NULL, *array_buf = NULL; > void *parg = (void *)arg; > long err = -EINVAL; > bool has_array_args; > @@ -3318,27 +3318,21 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg, > has_array_args = err; > > if (has_array_args) { > - /* > - * When adding new types of array args, make sure that the > - * parent argument to ioctl (which contains the pointer to the > - * array) fits into sbuf (so that mbuf will still remain > - * unused up to here). > - */ > - mbuf = kvmalloc(array_size, GFP_KERNEL); > + array_buf = kvmalloc(array_size, GFP_KERNEL); > err = -ENOMEM; > - if (NULL == mbuf) > + if (array_buf == NULL) if (!array_buf) ? > goto out_array_args; > err = -EFAULT; > if (in_compat_syscall()) > - err = v4l2_compat_get_array_args(file, mbuf, user_ptr, > - array_size, orig_cmd, > - parg); > + err = v4l2_compat_get_array_args(file, array_buf, > + user_ptr, array_size, > + orig_cmd, parg); > else > - err = copy_from_user(mbuf, user_ptr, array_size) ? > + err = copy_from_user(array_buf, user_ptr, array_size) ? > -EFAULT : 0; > if (err) > goto out_array_args; > - *kernel_ptr = mbuf; > + *kernel_ptr = array_buf; > } > > /* Handles IOCTL */ > @@ -3360,12 +3354,13 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg, > if (in_compat_syscall()) { > int put_err; > > - put_err = v4l2_compat_put_array_args(file, user_ptr, mbuf, > - array_size, orig_cmd, > - parg); > + put_err = v4l2_compat_put_array_args(file, user_ptr, > + array_buf, > + array_size, > + orig_cmd, parg); > if (put_err) > err = put_err; > - } else if (copy_to_user(user_ptr, mbuf, array_size)) { > + } else if (copy_to_user(user_ptr, array_buf, array_size)) { > err = -EFAULT; > } > goto out_array_args; > @@ -3381,6 +3376,7 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg, > if (video_put_user((void __user *)arg, parg, cmd, orig_cmd)) > err = -EFAULT; > out: > + kvfree(array_buf); > kvfree(mbuf); > return err; > } >
On 1/14/21 12:50 PM, Bingbu Cao wrote: > Sakari, > > On 12/21/20 4:11 AM, Sakari Ailus wrote: >> When an IOCTL with argument size larger than 128 that also used array >> arguments were handled, two memory allocations were made but alas, only >> the latter one of them was released. This happened because there was only >> a single local variable to hold such a temporary allocation. >> >> Fix this by adding separate variables to hold the pointers to the >> temporary allocations. >> >> Reported-by: Arnd Bergmann <arnd@kernel.org> >> Reported-by: syzbot+1115e79c8df6472c612b@syzkaller.appspotmail.com >> Fixes: d14e6d76ebf7 ("[media] v4l: Add multi-planar ioctl handling code") >> Cc: stable@vger.kernel.org >> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> >> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> >> --- >> drivers/media/v4l2-core/v4l2-ioctl.c | 32 ++++++++++++---------------- >> 1 file changed, 14 insertions(+), 18 deletions(-) >> >> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c >> index 3198abdd538c..9906b41004e9 100644 >> --- a/drivers/media/v4l2-core/v4l2-ioctl.c >> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c >> @@ -3283,7 +3283,7 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg, >> v4l2_kioctl func) >> { >> char sbuf[128]; >> - void *mbuf = NULL; >> + void *mbuf = NULL, *array_buf = NULL; >> void *parg = (void *)arg; >> long err = -EINVAL; >> bool has_array_args; >> @@ -3318,27 +3318,21 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg, >> has_array_args = err; >> >> if (has_array_args) { >> - /* >> - * When adding new types of array args, make sure that the >> - * parent argument to ioctl (which contains the pointer to the >> - * array) fits into sbuf (so that mbuf will still remain >> - * unused up to here). >> - */ >> - mbuf = kvmalloc(array_size, GFP_KERNEL); >> + array_buf = kvmalloc(array_size, GFP_KERNEL); >> err = -ENOMEM; >> - if (NULL == mbuf) >> + if (array_buf == NULL) > > if (!array_buf) > ? > Please ignore my previous comment, as the patch was landed. :) ....
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c index 3198abdd538c..9906b41004e9 100644 --- a/drivers/media/v4l2-core/v4l2-ioctl.c +++ b/drivers/media/v4l2-core/v4l2-ioctl.c @@ -3283,7 +3283,7 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg, v4l2_kioctl func) { char sbuf[128]; - void *mbuf = NULL; + void *mbuf = NULL, *array_buf = NULL; void *parg = (void *)arg; long err = -EINVAL; bool has_array_args; @@ -3318,27 +3318,21 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg, has_array_args = err; if (has_array_args) { - /* - * When adding new types of array args, make sure that the - * parent argument to ioctl (which contains the pointer to the - * array) fits into sbuf (so that mbuf will still remain - * unused up to here). - */ - mbuf = kvmalloc(array_size, GFP_KERNEL); + array_buf = kvmalloc(array_size, GFP_KERNEL); err = -ENOMEM; - if (NULL == mbuf) + if (array_buf == NULL) goto out_array_args; err = -EFAULT; if (in_compat_syscall()) - err = v4l2_compat_get_array_args(file, mbuf, user_ptr, - array_size, orig_cmd, - parg); + err = v4l2_compat_get_array_args(file, array_buf, + user_ptr, array_size, + orig_cmd, parg); else - err = copy_from_user(mbuf, user_ptr, array_size) ? + err = copy_from_user(array_buf, user_ptr, array_size) ? -EFAULT : 0; if (err) goto out_array_args; - *kernel_ptr = mbuf; + *kernel_ptr = array_buf; } /* Handles IOCTL */ @@ -3360,12 +3354,13 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg, if (in_compat_syscall()) { int put_err; - put_err = v4l2_compat_put_array_args(file, user_ptr, mbuf, - array_size, orig_cmd, - parg); + put_err = v4l2_compat_put_array_args(file, user_ptr, + array_buf, + array_size, + orig_cmd, parg); if (put_err) err = put_err; - } else if (copy_to_user(user_ptr, mbuf, array_size)) { + } else if (copy_to_user(user_ptr, array_buf, array_size)) { err = -EFAULT; } goto out_array_args; @@ -3381,6 +3376,7 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg, if (video_put_user((void __user *)arg, parg, cmd, orig_cmd)) err = -EFAULT; out: + kvfree(array_buf); kvfree(mbuf); return err; }
When an IOCTL with argument size larger than 128 that also used array arguments were handled, two memory allocations were made but alas, only the latter one of them was released. This happened because there was only a single local variable to hold such a temporary allocation. Fix this by adding separate variables to hold the pointers to the temporary allocations. Reported-by: Arnd Bergmann <arnd@kernel.org> Reported-by: syzbot+1115e79c8df6472c612b@syzkaller.appspotmail.com Fixes: d14e6d76ebf7 ("[media] v4l: Add multi-planar ioctl handling code") Cc: stable@vger.kernel.org Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> --- drivers/media/v4l2-core/v4l2-ioctl.c | 32 ++++++++++++---------------- 1 file changed, 14 insertions(+), 18 deletions(-)