Messages in this thread Patch in this message | | | Date | Mon, 4 Jul 2022 14:27:23 +0200 | Subject | Re: [PATCH 1/2] drm: Use size_t type for len variable in drm_copy_field() | From | Thomas Zimmermann <> |
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Am 01.07.22 um 14:07 schrieb Javier Martinez Canillas: > The strlen() function returns a size_t which is an unsigned int on 32-bit > arches and an unsigned long on 64-bit arches. But in the drm_copy_field() > function, the strlen() return value is assigned to an 'int len' variable. > > Later, the len variable is passed as copy_from_user() third argument that > is an unsigned long parameter as well. > > In theory, this can lead to an integer overflow via type conversion. Since > the assignment happens to a signed int lvalue instead of a size_t lvalue. > > In practice though, that's unlikely since the values copied are set by DRM > drivers and not controlled by userspace. But using a size_t for len is the > correct thing to do anyways. > > Reported-by: Peter Robinson <pbrobinson@gmail.com> > Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
> --- > > drivers/gpu/drm/drm_ioctl.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c > index 8faad23dc1d8..e1b9a03e619c 100644 > --- a/drivers/gpu/drm/drm_ioctl.c > +++ b/drivers/gpu/drm/drm_ioctl.c > @@ -472,7 +472,7 @@ EXPORT_SYMBOL(drm_invalid_op); > */ > static int drm_copy_field(char __user *buf, size_t *buf_len, const char *value) > { > - int len; > + size_t len; > > /* don't overflow userbuf */ > len = strlen(value);
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev [unhandled content-type:application/pgp-signature]
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