Linux kernel -stable discussions
 help / color / mirror / Atom feed
* FAILED: patch "[PATCH] nvmet: fix pre-auth out-of-bounds heap read in Discovery Get" failed to apply to 6.6-stable tree
@ 2026-07-15 10:20 gregkh
  2026-07-20 17:15 ` [PATCH 6.6.y 1/4] nvme: rename nvme_sc_to_pr_err to nvme_status_to_pr_err Sasha Levin
  0 siblings, 1 reply; 6+ messages in thread
From: gregkh @ 2026-07-15 10:20 UTC (permalink / raw)
  To: hexlabsecurity, hch, kbusch, kch; +Cc: stable


The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 53cd102a7a56079b11b897835bd9b94c14e6322c
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026071540-stiffly-shrill-b8b3@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 53cd102a7a56079b11b897835bd9b94c14e6322c Mon Sep 17 00:00:00 2001
From: Bryam Vargas <hexlabsecurity@proton.me>
Date: Wed, 27 May 2026 15:00:00 -0500
Subject: [PATCH] nvmet: fix pre-auth out-of-bounds heap read in Discovery Get
 Log Page

nvmet_execute_disc_get_log_page() validates only the dword alignment
of the host-supplied Log Page Offset (lpo).  The 64-bit offset is then
added to a small kzalloc'd buffer that holds the discovery log page
and the result is passed straight to nvmet_copy_to_sgl(), which
memcpy()s data_len bytes out to the host with no source-side bound
check:

    u64 offset      = nvmet_get_log_page_offset(req->cmd);  /* 64-bit host */
    size_t data_len = nvmet_get_log_page_len(req->cmd);     /* 32-bit host */
    ...
    if (offset & 0x3) { ... }                               /* only check */
    ...
    alloc_len = sizeof(*hdr) + entry_size * discovery_log_entries(req);
    buffer = kzalloc(alloc_len, GFP_KERNEL);
    ...
    status = nvmet_copy_to_sgl(req, 0, buffer + offset, data_len);

The Discovery controller is unauthenticated -- nvmet_host_allowed()
returns true unconditionally for the discovery subsystem -- so the call
is reachable pre-authentication by any TCP/RDMA/FC peer that can reach
the nvmet target.  With a discovery log page of ~1 KiB, an attacker
requesting up to 4 KiB starting at offset == alloc_len reads the next
slab page out and gets its content returned over the fabric (an
empirical run on a default nvmet-tcp loopback target leaked 81
canonical kernel pointers in one Get Log Page response).  Pointing the
offset at unmapped kernel memory faults the in-kernel memcpy and
crashes (or panics, on panic_on_oops=1) the target host instead.

The attacker-controlled source-side offset pattern
"nvmet_copy_to_sgl(req, 0, buffer + ATTACKER_OFFSET, ...)" is unique
to nvmet_execute_disc_get_log_page in the entire nvmet codebase: every
other Get Log Page handler in admin-cmd.c either ignores lpo (and
silently starts every response at offset 0) or tracks a local
destination offset with a fixed source pointer.

Validate the host-supplied offset against the log page size, cap the
copy length to what is actually available, and zero-fill any remainder
of the host transfer buffer.  The zero-fill matches the existing
short-response pattern in nvmet_execute_get_log_changed_ns()
(admin-cmd.c) and prevents leaking transport SGL contents when the
host asks for more bytes than the log page contains.

Fixes: a07b4970f464 ("nvmet: add a generic NVMe target")
Cc: stable@vger.kernel.org
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>

diff --git a/drivers/nvme/target/discovery.c b/drivers/nvme/target/discovery.c
index e9b35549e254..114869d16a1f 100644
--- a/drivers/nvme/target/discovery.c
+++ b/drivers/nvme/target/discovery.c
@@ -166,6 +166,7 @@ static void nvmet_execute_disc_get_log_page(struct nvmet_req *req)
 	u64 offset = nvmet_get_log_page_offset(req->cmd);
 	size_t data_len = nvmet_get_log_page_len(req->cmd);
 	size_t alloc_len;
+	size_t copy_len;
 	struct nvmet_subsys_link *p;
 	struct nvmet_port *r;
 	u32 numrec = 0;
@@ -242,7 +243,27 @@ static void nvmet_execute_disc_get_log_page(struct nvmet_req *req)
 
 	up_read(&nvmet_config_sem);
 
-	status = nvmet_copy_to_sgl(req, 0, buffer + offset, data_len);
+	/*
+	 * Validate the host-supplied log page offset before copying out.
+	 * Without this check, the host controls a 64-bit byte offset into
+	 * a small kzalloc'd buffer: a value past the log page lets the
+	 * subsequent memcpy read adjacent kernel heap, and a value aimed
+	 * at unmapped kernel memory faults the in-kernel copy and crashes
+	 * the target host. The Discovery controller is unauthenticated,
+	 * so the bug is reachable from any reachable fabric peer.
+	 */
+	if (offset > alloc_len) {
+		req->error_loc =
+			offsetof(struct nvme_get_log_page_command, lpo);
+		status = NVME_SC_INVALID_FIELD | NVME_STATUS_DNR;
+		goto out_free_buffer;
+	}
+
+	copy_len = min_t(size_t, data_len, alloc_len - offset);
+	status = nvmet_copy_to_sgl(req, 0, buffer + offset, copy_len);
+	if (!status && copy_len < data_len)
+		status = nvmet_zero_sgl(req, copy_len, data_len - copy_len);
+out_free_buffer:
 	kfree(buffer);
 out:
 	nvmet_req_complete(req, status);


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* FAILED: patch "[PATCH] nvmet-tcp: bound SGL data length before allocating command" failed to apply to 6.6-stable tree
@ 2026-08-25  8:07 gregkh
  2026-08-26 12:57 ` [PATCH 6.6.y 1/4] nvme: rename nvme_sc_to_pr_err to nvme_status_to_pr_err Sasha Levin
  0 siblings, 1 reply; 6+ messages in thread
From: gregkh @ 2026-08-25  8:07 UTC (permalink / raw)
  To: security, hch, kbusch; +Cc: stable


The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 4a3f00262a044e8e15064b1a6860968bf0500bf4
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026082515-mobilize-facelift-6d03@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4a3f00262a044e8e15064b1a6860968bf0500bf4 Mon Sep 17 00:00:00 2001
From: Ibrahim Hashimov <security@auditcode.ai>
Date: Thu, 9 Jul 2026 15:25:33 +0200
Subject: [PATCH] nvmet-tcp: bound SGL data length before allocating command
 buffers

nvmet_tcp_map_data() reads the host-controlled 32-bit sgl->length
and, for the in-capsule offset descriptor (type 0x01), checks it
against port->inline_data_size before use. Any other SGL descriptor
type -- including the non-inline transport SGL data-block descriptor
(type (NVME_TRANSPORT_SGL_DATA_DESC << 4) | NVME_SGL_FMT_TRANSPORT_A,
the type a real host uses for out-of-capsule writes) skips that check
entirely and falls straight through to:

	cmd->req.sg = sgl_alloc(len, GFP_KERNEL, &cmd->req.sg_cnt);

with len taken directly from the wire, unbounded up to 4 GiB.

nvmet_req_init() only parses the command and never inspects
sgl->length, and nvmet_check_transfer_len() -- the only other place
transfer_len is validated -- runs later, from req->execute(), after
the allocation has already happened. For a write command the target
responds with an R2T and parks the command waiting for the host to
send the data; if the host (or an unauthenticated peer that simply
never follows up) never does, the sgl_alloc() buffer stays resident
for the life of the command. NVMe/TCP has no mandatory authentication
in the default configuration, so any peer able to reach the target
portal and complete a Fabrics connect can drive this with a single
crafted command, repeatable across queues and connections for
amplification. This is unbounded kernel memory allocation
triggered by a remote, effectively unauthenticated peer.

Validate len against the same NVMET_TCP_MAXH2CDATA ceiling this file
already uses to bound per-PDU H2C data, for every SGL descriptor type,
before doing any allocation. This closes the gap for the non-inline
descriptor while leaving the existing, tighter inline_data_size check
in place for the in-capsule case.

Runtime-verified on a v6.19 KASAN stand: with this bound in place, a
crafted write command carrying an oversized non-inline SGL length is
rejected before sgl_alloc() runs, where the same request previously
drove an unbounded ~256 MiB kernel allocation (up to 4 GiB) that
stayed resident pending an R2T the host never satisfies.

Fixes: 872d26a391da ("nvmet-tcp: add NVMe over TCP target driver")
Cc: stable@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ibrahim Hashimov <security@auditcode.ai>
Assisted-by: AuditCode-AI:2026.07
Signed-off-by: Keith Busch <kbusch@kernel.org>

diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index cb6d37798d74..e4f603b2ace7 100644
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -422,6 +422,19 @@ static int nvmet_tcp_map_data(struct nvmet_tcp_cmd *cmd)
 	if (!len)
 		return 0;
 
+	/*
+	 * inline_data_size only bounds the in-capsule (type 0x01) SGL
+	 * descriptor below. A non-inline transport SGL data-block
+	 * descriptor skips that check entirely and would otherwise reach
+	 * sgl_alloc() with an attacker-controlled len of up to 4 GiB,
+	 * pinning that much kernel memory for a command that may never
+	 * complete. Bound every descriptor type here, before allocating
+	 * anything, using the same ceiling this file already applies to
+	 * per-PDU H2C data.
+	 */
+	if (len > NVMET_TCP_MAXH2CDATA)
+		return NVME_SC_SGL_INVALID_DATA | NVME_STATUS_DNR;
+
 	if (sgl->type == ((NVME_SGL_FMT_DATA_DESC << 4) |
 			  NVME_SGL_FMT_OFFSET)) {
 		if (!nvme_is_write(cmd->req.cmd))


^ permalink raw reply related	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-08-26 12:57 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-07-15 10:20 FAILED: patch "[PATCH] nvmet: fix pre-auth out-of-bounds heap read in Discovery Get" failed to apply to 6.6-stable tree gregkh
2026-07-20 17:15 ` [PATCH 6.6.y 1/4] nvme: rename nvme_sc_to_pr_err to nvme_status_to_pr_err Sasha Levin
2026-07-20 17:15   ` [PATCH 6.6.y 2/4] nvme: fix status magic numbers Sasha Levin
2026-07-20 17:15   ` [PATCH 6.6.y 3/4] nvme: rename CDR/MORE/DNR to NVME_STATUS_* Sasha Levin
2026-07-20 17:15   ` [PATCH 6.6.y 4/4] nvmet: fix pre-auth out-of-bounds heap read in Discovery Get Log Page Sasha Levin
  -- strict thread matches above, loose matches on Subject: below --
2026-08-25  8:07 FAILED: patch "[PATCH] nvmet-tcp: bound SGL data length before allocating command" failed to apply to 6.6-stable tree gregkh
2026-08-26 12:57 ` [PATCH 6.6.y 1/4] nvme: rename nvme_sc_to_pr_err to nvme_status_to_pr_err Sasha Levin
2026-08-26 12:57   ` [PATCH 6.6.y 3/4] nvme: rename CDR/MORE/DNR to NVME_STATUS_* Sasha Levin

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox