On 4/11/24 13:08, Mikhail Kobuk wrote:> When Output Resource (dcb->or) value is assigned in
> fabricate_dcb_output(), there may be out of bounds access to
> dac_users array in case dcb->or is zero because ffs(dcb->or) is
> used as index there.
> The 'or' argument of fabricate_dcb_output() must be interpreted as
a
> number of bit to set, not value.
>
> Utilize macros from 'enum nouveau_or' in calls instead of
hardcoding.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: 2e5702aff395 ("drm/nouveau: fabricate DCB encoder table for
iMac G4")
> Fixes: 670820c0e6a9 ("drm/nouveau: Workaround incorrect DCB entry on a
GeForce3 Ti 200.")
> Signed-off-by: Mikhail Kobuk <m.kobuk at ispras.ru>
Applied to drm-misc-fixes, thanks!
> ---
> Changes in v2:
> - Instead of checking ffs(dcb->or), adjust function calls to match
> argument semantics
> - Link to v1: https://lore.kernel.org/all/20240331064552.6112-1-m.kobuk at
ispras.ru/
>
> drivers/gpu/drm/nouveau/nouveau_bios.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_bios.c
b/drivers/gpu/drm/nouveau/nouveau_bios.c
> index 479effcf607e..79cfab53f80e 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_bios.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_bios.c
> @@ -23,6 +23,7 @@
> */
>
> #include "nouveau_drv.h"
> +#include "nouveau_bios.h"
> #include "nouveau_reg.h"
> #include "dispnv04/hw.h"
> #include "nouveau_encoder.h"
> @@ -1677,7 +1678,7 @@ apply_dcb_encoder_quirks(struct drm_device *dev, int
idx, u32 *conn, u32 *conf)
> */
> if (nv_match_device(dev, 0x0201, 0x1462, 0x8851)) {
> if (*conn == 0xf2005014 && *conf == 0xffffffff) {
> - fabricate_dcb_output(dcb, DCB_OUTPUT_TMDS, 1, 1, 1);
> + fabricate_dcb_output(dcb, DCB_OUTPUT_TMDS, 1, 1, DCB_OUTPUT_B);
> return false;
> }
> }
> @@ -1763,26 +1764,26 @@ fabricate_dcb_encoder_table(struct drm_device *dev,
struct nvbios *bios)
> #ifdef __powerpc__
> /* Apple iMac G4 NV17 */
> if (of_machine_is_compatible("PowerMac4,5")) {
> - fabricate_dcb_output(dcb, DCB_OUTPUT_TMDS, 0, all_heads, 1);
> - fabricate_dcb_output(dcb, DCB_OUTPUT_ANALOG, 1, all_heads, 2);
> + fabricate_dcb_output(dcb, DCB_OUTPUT_TMDS, 0, all_heads, DCB_OUTPUT_B);
> + fabricate_dcb_output(dcb, DCB_OUTPUT_ANALOG, 1, all_heads,
DCB_OUTPUT_C);
> return;
> }
> #endif
>
> /* Make up some sane defaults */
> fabricate_dcb_output(dcb, DCB_OUTPUT_ANALOG,
> - bios->legacy.i2c_indices.crt, 1, 1);
> + bios->legacy.i2c_indices.crt, 1, DCB_OUTPUT_B);
>
> if (nv04_tv_identify(dev, bios->legacy.i2c_indices.tv) >= 0)
> fabricate_dcb_output(dcb, DCB_OUTPUT_TV,
> bios->legacy.i2c_indices.tv,
> - all_heads, 0);
> + all_heads, DCB_OUTPUT_A);
>
> else if (bios->tmds.output0_script_ptr ||
> bios->tmds.output1_script_ptr)
> fabricate_dcb_output(dcb, DCB_OUTPUT_TMDS,
> bios->legacy.i2c_indices.panel,
> - all_heads, 1);
> + all_heads, DCB_OUTPUT_B);
> }
>
> static int