From fb18802a338b36f675a388fc03d2aa504a0d0899 Mon Sep 17 00:00:00 2001 From: Sakari Ailus Date: Sat, 19 Dec 2020 23:29:58 +0100 Subject: [PATCH] media: v4l: ioctl: Fix memory leak in video_usercopy 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 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 Acked-by: Arnd Bergmann Acked-by: Hans Verkuil Reviewed-by: Laurent Pinchart Signed-off-by: Mauro Carvalho Chehab --- 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 3198abd..9906b41 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 @@ out_array_args: if (video_put_user((void __user *)arg, parg, cmd, orig_cmd)) err = -EFAULT; out: + kvfree(array_buf); kvfree(mbuf); return err; } -- 2.7.4