[PULL,1/2] hw/misc: use extract64 instead of 1 << i

Commit Message

Paolo Bonzini March 17, 2025, 3:21 p.m. UTC

From: Tigran Sogomonian <[e-mail]>

1 << i is casted to uint64_t while bitwise and with val.
So this value may become 0xffffffff80000000 but only
31th "start" bit is required.
Use the bitfield extract() API instead.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Tigran Sogomonian <[e-mail]>
Reviewed-by: Alex Bennée <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Paolo Bonzini <[e-mail]>
---
 hw/misc/mps2-fpgaio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/hw/misc/mps2-fpgaio.c b/hw/misc/mps2-fpgaio.c
index d07568248d6..04a3da5db05 100644
--- a/hw/misc/mps2-fpgaio.c
+++ b/hw/misc/mps2-fpgaio.c
@@ -198,7 +198,7 @@  static void mps2_fpgaio_write(void *opaque, hwaddr offset, uint64_t value,
 
             s->led0 = value & MAKE_64BIT_MASK(0, s->num_leds);
             for (i = 0; i < s->num_leds; i++) {
-                led_set_state(s->led[i], value & (1 << i));
+                led_set_state(s->led[i], extract64(value, i, 1));
             }
         }
         break;