RISC-V: KVM: Fix sdata leak and stale snapshot_addr in snapshot_set_shmem

A guest may call SBI_PMU_SNAPSHOT_SET_SHMEM repeatedly. Each call
overwrites kvpmu->sdata without freeing the old buffer (memory leak),
and if a later kvm_vcpu_write_guest() fails, the error path frees
sdata but leaves snapshot_addr stale. A subsequent
SBI_PMU_COUNTER_START then passes the INVALID_GPA check and crashes
the host with a NULL buffer in kvm_vcpu_read_guest().

Fix this by clearing the previously installed snapshot area before
installing a new one, which keeps sdata and snapshot_addr consistent.
The SBI spec suggests a single invocation but defines no error code
for repeated calls, so KVM must tolerate them.

Fixes: c2f41ddbcdd756 ("RISC-V: KVM: Implement SBI PMU Snapshot feature")
Cc: stable@vger.kernel.org
Signed-off-by: Zongmin Zhou <zhouzongmin@kylinos.cn>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260826064117.58029-1-min_halo@163.com
Signed-off-by: Anup Patel <anup@brainfault.org>

0 files changed, 0 insertions, 0 deletions