While the Packet Number Register is 6-bit wide and could hold
up to 64 packets [*] our implementation is clamped at 4 packets.
Reproducer:
$ cat << EOF | qemu-system-arm -display none \
-machine mainstone,accel=qtest \
-qtest stdio
outl 0xcf8 0x80000010
outl 0xcfc 0x10000300
outl 0xcf8 0x80000004
outl 0xcfc 0x07
writel 0x1000030c 0x66027cd6
writel 0x10000300 0x64af8eda
readw 0x10000308
EOF
hw/net/smc91c111.c:607:24: runtime error:
index 175 out of bounds for type 'uint8_t[4][2048]' (aka 'unsigned
char[4][2048]')
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
=================================================================
==397944==ERROR: AddressSanitizer: SEGV on unknown address 0x629000077db4
(pc 0x56272aed3b8d bp 0x7ffd1471f290 sp 0x7ffd1471ea20 T0)
==397944==The signal is caused by a READ memory access.
#0 0x56272aed3b8d in smc91c111_readb hw/net/smc91c111.c:607:24
#1 0x56272aecfd61 in smc91c111_readfn hw/net/smc91c111.c:650:16
#2 0x56272d4b228b in memory_region_read_accessor system/memory.c:445:11
#3 0x56272d46fb85 in access_with_adjusted_size system/memory.c:573:18
#4 0x56272d46c58e in memory_region_dispatch_read1 system/memory.c:1426:16
#5 0x56272d46bcd7 in memory_region_dispatch_read system/memory.c:1459:9
#6 0x56272d4e8e03 in flatview_read_continue_step system/physmem.c:2794:18
#7 0x56272d4e871e in flatview_read_continue system/physmem.c:2835:19
#8 0x56272d4e98b8 in flatview_read system/physmem.c:2865:12
#9 0x56272d4e9388 in address_space_read_full system/physmem.c:2878:18
#10 0x56272d6e7840 in address_space_read include/exec/memory.h:3026:18
...
Broken since model introduction in commit 80337b66a8.
[*] LAN91C111 DS00002276A.pdf, chapter 8.17, Packet Number Register
Reported-by: Will Lester
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2268
Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org>
---
hw/net/smc91c111.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/net/smc91c111.c b/hw/net/smc91c111.c
index 702d0e8e83..286298bf06 100644
--- a/hw/net/smc91c111.c
+++ b/hw/net/smc91c111.c
@@ -429,7 +429,7 @@ static void smc91c111_writeb(void *opaque, hwaddr offset,
/* Ignore. */
return;
case 2: /* Packet Number Register */
- s->packet_num = value;
+ s->packet_num = value & (NUM_PACKETS - 1);
return;
case 3: case 4: case 5:
/* Should be readonly, but linux writes to them anyway. Ignore. */
--
2.41.0
