From: Anastasia Belova Date: Mon, 13 Jan 2025 12:35:32 +0000 (+0000) Subject: hw/arm_sysctl: fix extracting 31th bit of val X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=906853e1427a1ff89c64c0ebb6faa9c68f0a5d74;p=qemu.git hw/arm_sysctl: fix extracting 31th bit of val 1 << 31 is casted to uint64_t while bitwise and with val. So this value may become 0xffffffff80000000 but only 31th "start" bit is required. This is not possible in practice because the MemoryRegionOps uses the default max access size of 4 bytes and so none of the upper bytes of val will be set, but the bitfield extract API is clearer anyway. Use the bitfield extract() API instead. Found by Linux Verification Center (linuxtesting.org) with SVACE. Signed-off-by: Anastasia Belova Message-id: 20241220125429.7552-1-abelova@astralinux.ru Reviewed-by: Peter Maydell [PMM: add clarification to commit message] Signed-off-by: Peter Maydell --- diff --git a/hw/misc/arm_sysctl.c b/hw/misc/arm_sysctl.c index 016a302e67..01663407ec 100644 --- a/hw/misc/arm_sysctl.c +++ b/hw/misc/arm_sysctl.c @@ -520,7 +520,7 @@ static void arm_sysctl_write(void *opaque, hwaddr offset, * as zero. */ s->sys_cfgctrl = val & ~((3 << 18) | (1 << 31)); - if (val & (1 << 31)) { + if (extract64(val, 31, 1)) { /* Start bit set -- actually do something */ unsigned int dcc = extract32(s->sys_cfgctrl, 26, 4); unsigned int function = extract32(s->sys_cfgctrl, 20, 6);