From: Richard Henderson <richard.hender...@linaro.org>
The third argument of the syscall contains the size of the
cpu mask in bytes, not bits. Nor is the size rounded up to
a multiple of sizeof(abi_ulong).
Cc: qemu-sta...@nongnu.org
Reported-by: Andreas Schwab <sch...@suse.de>
Fixes: 9e1c7d982d7 ("linux-user/riscv: Add syscall riscv_hwprobe")
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
Reviewed-by: Alistair Francis <alistair.fran...@wdc.com>
Message-ID: <20250308225902.1208237-3-richard.hender...@linaro.org>
Signed-off-by: Alistair Francis <alistair.fran...@wdc.com>
---
linux-user/syscall.c | 55 +++++++++++++++++++++++---------------------
1 file changed, 29 insertions(+), 26 deletions(-)
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index b32de763f7..8bfe4912e1 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -9119,35 +9119,38 @@ static void risc_hwprobe_fill_pairs(CPURISCVState *env,
}
}
-static int cpu_set_valid(abi_long arg3, abi_long arg4)
+/*
+ * If the cpumask_t of (target_cpus, cpusetsize) cannot be read: -EFAULT.
+ * If the cpumast_t has no bits set: -EINVAL.
+ * Otherwise the cpumask_t contains some bit set: 0.
+ * Unlike the kernel, we do not mask cpumask_t by the set of online cpus,
+ * nor bound the search by cpumask_size().
+ */
+static int nonempty_cpu_set(abi_ulong cpusetsize, abi_ptr target_cpus)
{
- int ret, i, tmp;
- size_t host_mask_size, target_mask_size;
- unsigned long *host_mask;
-
- /*
- * cpu_set_t represent CPU masks as bit masks of type unsigned long *.
- * arg3 contains the cpu count.
- */
- tmp = (8 * sizeof(abi_ulong));
- target_mask_size = ((arg3 + tmp - 1) / tmp) * sizeof(abi_ulong);
- host_mask_size = (target_mask_size + (sizeof(*host_mask) - 1)) &
- ~(sizeof(*host_mask) - 1);
-
- host_mask = alloca(host_mask_size);
-
- ret = target_to_host_cpu_mask(host_mask, host_mask_size,
- arg4, target_mask_size);
- if (ret != 0) {
- return ret;
- }
+ unsigned char *p = lock_user(VERIFY_READ, target_cpus, cpusetsize, 1);
+ int ret = -TARGET_EFAULT;
- for (i = 0 ; i < host_mask_size / sizeof(*host_mask); i++) {
- if (host_mask[i] != 0) {
- return 0;
+ if (p) {
+ ret = -TARGET_EINVAL;
+ /*
+ * Since we only care about the empty/non-empty state of the cpumask_t
+ * not the individual bits, we do not need to repartition the bits
+ * from target abi_ulong to host unsigned long.
+ *
+ * Note that the kernel does not round up cpusetsize to a multiple of
+ * sizeof(abi_ulong). After bounding cpusetsize by cpumask_size(),
+ * it copies exactly cpusetsize bytes into a zeroed buffer.
+ */
+ for (abi_ulong i = 0; i < cpusetsize; ++i) {
+ if (p[i]) {
+ ret = 0;
+ break;
+ }
}
+ unlock_user(p, target_cpus, 0);
}
- return -TARGET_EINVAL;
+ return ret;
}
static abi_long do_riscv_hwprobe(CPUArchState *cpu_env, abi_long arg1,
@@ -9164,7 +9167,7 @@ static abi_long do_riscv_hwprobe(CPUArchState *cpu_env,
abi_long arg1,
/* check cpu_set */
if (arg3 != 0) {
- ret = cpu_set_valid(arg3, arg4);
+ ret = nonempty_cpu_set(arg3, arg4);
if (ret != 0) {
return ret;
}
--
2.48.1
