drm: nv04: Fix out of bounds access

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@ispras.ru>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240411110854.16701-1-m.kobuk@ispras.ru

diff --git a/drivers/gpu/drm/nouveau/nouveau_bios.c b/drivers/gpu/drm/nouveau/nouveau_bios.c
index 479effcf607e261fac73361958a0a855cf90d315..79cfab53f80e259093b7ae0f04310f6470a3c930 100644 (file)
--- 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