From 808e530654a5354e6df78863a5d61e4d44e67235 Mon Sep 17 00:00:00 2001 From: Bryam Vargas Date: Sat, 20 Jun 2026 21:42:11 -0500 Subject: [PATCH] misc: nsm: bound the device-reported response length nsm_sendrecv_msg_locked() stores the virtqueue used-ring length reported by the NSM device into msg->resp.len without bounding it to the response buffer. A malicious or buggy backend can report a length larger than the response buffer; parse_resp_raw() then copies that many bytes out of the fixed buffer to user space, disclosing adjacent kernel heap (an out-of-bounds read). The request path already floors its length in fill_req_raw(); the response path lacks the symmetric check. Clamp the stored length to the size of the response buffer. Well-behaved devices report no more than the posted buffer size, so conforming traffic is unaffected. Fixes: b9873755a6c8 ("misc: Add Nitro Secure Module driver") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Reviewed-by: Alexander Graf Link: https://patch.msgid.link/20260620-b4-disp-a54b7dd6-v1-1-79d1f236a854@proton.me Signed-off-by: Greg Kroah-Hartman --- drivers/misc/nsm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/misc/nsm.c b/drivers/misc/nsm.c index e39ff00714f7..bb254ee65b84 100644 --- a/drivers/misc/nsm.c +++ b/drivers/misc/nsm.c @@ -243,7 +243,7 @@ static int nsm_sendrecv_msg_locked(struct nsm *nsm) goto cleanup; } - msg->resp.len = len; + msg->resp.len = min_t(unsigned int, len, sizeof(msg->resp.data)); rc = 0;