i am curious: what is the win to have a unsigned 64 bit integer in the first place ? re, wh ________________________________________ Von: Christian König <christian.koenig@xxxxxxx> Gesendet: Montag, 8. Februar 2021 10:17:42 An: Colin King; Alex Deucher; David Airlie; Daniel Vetter; Huang Rui; Junwei Zhang; amd-gfx@xxxxxxxxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx Cc: kernel-janitors@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx Betreff: Re: [PATCH] drm/amdgpu: fix potential integer overflow on shift of a int Am 08.02.21 um 00:07 schrieb Colin King: > From: Colin Ian King <colin.king@xxxxxxxxxxxxx> > > The left shift of int 32 bit integer constant 1 is evaluated using 32 > bit arithmetic and then assigned to an unsigned 64 bit integer. In the > case where *frag is 32 or more this can lead to an oveflow. Avoid this > by shifting 1ULL. Well that can't happen. Take a look at the code in that function: > max_frag = 31; ... > if (*frag >= max_frag) { > *frag = max_frag; > *frag_end = end & ~((1ULL << max_frag) - 1); > } else { > *frag_end = start + (1 << *frag); > } But I'm fine with applying the patch if it silences your warning. Regards, Christian. > > Addresses-Coverity: ("Unintentional integer overflow") > Fixes: dfcd99f6273e ("drm/amdgpu: meld together VM fragment and huge page handling") > Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx> > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c > index 9d19078246c8..53a925600510 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c > @@ -1412,7 +1412,7 @@ static void amdgpu_vm_fragment(struct amdgpu_vm_update_params *params, > *frag = max_frag; > *frag_end = end & ~((1ULL << max_frag) - 1); > } else { > - *frag_end = start + (1 << *frag); > + *frag_end = start + (1ULL << *frag); > } > } > _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel