From f687394af983df5660b6afae7e0d06969f3af206 Mon Sep 17 00:00:00 2001 From: Zhenhao Wan Date: Sat, 20 Jun 2026 12:33:15 +0800 Subject: [PATCH] cxl/features: bound fwctl command payload to the input buffer fwctl_cmd_rpc() copies cmd->in_len bytes into inbuf = kvzalloc(cmd->in_len) and passes inbuf and in_len to ->fw_rpc(). The CXL callback cxlctl_fw_rpc() ignores in_len and never checks the user-controlled op_size against it. cxlctl_set_feature() bounds op_size only from below (op_size <= sizeof(feat_in->hdr)) and then reads op_size - sizeof(hdr) bytes from feat_in->feat_data via cxl_set_feature(). With a small in_len and a large op_size the first memcpy() already reads past the kvzalloc(in_len) buffer; the out-of-bounds bytes are placed in the mailbox payload and sent to the device, and a large enough op_size can walk into unmapped memory and oops the kernel. The Get paths pin op_size to a fixed size but likewise read the input struct without checking in_len. Reject, at the single dispatch point, any request whose fixed header plus op_size does not fit in the copied-in buffer. The lower-bound test guards the subtraction and ensures op_size was copied in before it is read. Fixes: eb5dfcb9e36d ("cxl: Add support to handle user feature commands for set feature") Reported-by: Yuhao Jiang Signed-off-by: Zhenhao Wan Cc: stable@vger.kernel.org Reviewed-by: Jason Gunthorpe Link: https://patch.msgid.link/20260620-cxl-fwctl-oob-v1-1-5758e34d784a@gmail.com Signed-off-by: Dave Jiang --- drivers/cxl/core/features.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/cxl/core/features.c b/drivers/cxl/core/features.c index 85185af46b72..738a89863ee8 100644 --- a/drivers/cxl/core/features.c +++ b/drivers/cxl/core/features.c @@ -649,7 +649,13 @@ static void *cxlctl_fw_rpc(struct fwctl_uctx *uctx, enum fwctl_rpc_scope scope, struct cxl_memdev *cxlmd = fwctl_to_memdev(fwctl_dev); struct cxl_features_state *cxlfs = to_cxlfs(cxlmd->cxlds); const struct fwctl_rpc_cxl *rpc_in = in; - u16 opcode = rpc_in->opcode; + u16 opcode; + + if (in_len < sizeof(rpc_in->hdr) || + rpc_in->op_size > in_len - sizeof(rpc_in->hdr)) + return ERR_PTR(-EINVAL); + + opcode = rpc_in->opcode; if (!cxlctl_validate_hw_command(cxlfs, rpc_in, scope, opcode)) return ERR_PTR(-EINVAL);