From 48b13bfbdf94e683cc5b8c5cb35b5af4221e657f Mon Sep 17 00:00:00 2001 From: Sunday Clement Date: Wed, 13 May 2026 11:22:19 -0400 Subject: [PATCH] drm/amdkfd: Fix OOB memory exposure in get_wave_state() The get_wave_state() function for v9 trusts cp_hqd_cntl_stack_size and cp_hqd_cntl_stack_offset values read directly from the MQD, which are written by GPU microcode and fully attacker-controlled on the CRIU-restore path (via AMDKFD_IOC_RESTORE_PROCESS with H3). this leads to an unbounded copy_to_user() that can leak adjacent GTT/kernel memory. If offset > size, integer underflow produces a ~4 GiB read length, if size is set to 1 MiB against a 4 KiB allocation, we leak 1 MiB of adjacent kernel memory (other queues' MQDs, ring buffers, KASLR pointers). Fix by clamping both cp_hqd_cntl_stack_size to the actual allocated buffer size (q->ctl_stack_size) and cp_hqd_cntl_stack_offset to the clamped size before performing arithmetic and copy_to_user(). This ensures we never read beyond the allocated kernel BO regardless of attacker-supplied MQD field values. Signed-off-by: Sunday Clement Acked-by: Alex Deucher Signed-off-by: Alex Deucher (cherry picked from commit 7ef144458f48d5589e36f1b3d83e83db2e5c5ba5) --- drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c index e8f97de9d6e4..f6d9d81003dc 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c @@ -364,11 +364,15 @@ static int get_wave_state(struct mqd_manager *mm, void *mqd, { struct v9_mqd *m; struct kfd_context_save_area_header header; + u32 cntl_stack_size; + u32 cntl_stack_offset; /* Control stack is located one page after MQD. */ void *mqd_ctl_stack = (void *)((uintptr_t)mqd + AMDGPU_GPU_PAGE_SIZE); m = get_mqd(mqd); + cntl_stack_size = min_t(u32, m->cp_hqd_cntl_stack_size, q->ctl_stack_size); + cntl_stack_offset = min_t(u32, m->cp_hqd_cntl_stack_offset, cntl_stack_size); *ctl_stack_used_size = m->cp_hqd_cntl_stack_size - m->cp_hqd_cntl_stack_offset; @@ -384,9 +388,10 @@ static int get_wave_state(struct mqd_manager *mm, void *mqd, if (copy_to_user(ctl_stack, &header, sizeof(header.wave_state))) return -EFAULT; - if (copy_to_user(ctl_stack + m->cp_hqd_cntl_stack_offset, - mqd_ctl_stack + m->cp_hqd_cntl_stack_offset, - *ctl_stack_used_size)) + *ctl_stack_used_size = cntl_stack_size - cntl_stack_offset; + + if (copy_to_user(ctl_stack + cntl_stack_offset, mqd_ctl_stack + cntl_stack_offset, + *ctl_stack_used_size)) return -EFAULT; return 0;