[PATCH net] octeontx2-af: validate body pcifunc in rvu_mbox_handler_rep_event_notify

[Michael Bommarito <michael.bommarito@gmail.com>]

rvu_mbox_handler_rep_event_notify() in drivers/net/ethernet/marvell/
octeontx2/af/rvu_rep.c queues a sender-controlled REP_EVENT_NOTIFY
request body verbatim, and rvu_rep_up_notify() then forwards
event->pcifunc (the nested body field, distinct from the
AF-normalised header pcifunc) into rvu_get_pfvf(), rvu_get_pf() and
the AF->PF mailbox device index without any bounds check.

A VF attached to a PF that has been put into switchdev
representor mode reaches this path: the VF mailbox handler
otx2_pfvf_mbox_handler() forwards every message id including
MBOX_MSG_REP_EVENT_NOTIFY to AF without an allowlist, and the AF
dispatcher rewrites only msg->pcifunc, leaving struct
rep_event::pcifunc attacker-controlled.  The sibling
rvu_mbox_handler_esw_cfg() refuses requests whose header pcifunc
is not rvu->rep_pcifunc; this handler has no equivalent gate.

An out-of-range body pcifunc selects an &rvu->pf[]/&rvu->hwvf[]
element past the allocated array and, for RVU_EVENT_MAC_ADDR_CHANGE,
turns into a six-byte attacker-chosen OOB ether_addr_copy() target
inside the queued worker; KASAN reports a slab-out-of-bounds write
in rvu_rep_wq_handler.

Reject malformed requests at the handler entry by gating on
is_pf_func_valid(), which is already the canonical PF/VF range check
in this driver; expose it via rvu.h so callers in rvu_rep.c can use
it instead of open-coding the same range arithmetic.

Fixes: b8fea84a0468 ("octeontx2-pf: Add support to sync link state between representor and VFs")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
---

Reproduction
============

Tree: net mainline at v7.1-rc4 (5200f5f493f7), x86_64 QEMU,
CONFIG_KASAN_GENERIC=y, CONFIG_KUNIT=y, CONFIG_OCTEONTX2_AF=y.

Conditions: rvu_af bound to RVU AF hardware in production, or a
synthetic struct rvu in the KUnit harness used for this report.
No sysctl, capability, or namespace gate on the VF mailbox side
once switchdev/SR-IOV is provisioned.

Harness: an out-of-tree KUnit module invokes
rvu_mbox_handler_rep_event_notify() directly on a synthetic struct
rvu allocated via kunit_kzalloc with a one-PF rvu->pf[] array and
rvu->hw->total_pfs == 1.  The crafted struct rep_event sets
hdr.sig = OTX2_MBOX_REQ_SIG, hdr.id = MBOX_MSG_REP_EVENT_NOTIFY,
header pcifunc 0, nested body pcifunc 2 << RVU_OTX2_PFVF_PF_SHIFT
(one PF past the synthetic array), event = RVU_EVENT_MAC_ADDR_CHANGE,
and a six-byte payload.  This matches the bytes a forwarded VF
mailbox message places at the AF mbox.

Stock:
  BUG: KASAN: slab-out-of-bounds in rvu_rep_wq_handler+0x100/0x280
  Write of size 4 at addr ffff8880022bff03 by task kworker/0:0/9
  Workqueue: rep_evt_kunit_wq rvu_rep_wq_handler
  allocated by kunit_kmalloc_array+0x1b/0x50 -> make_synth_rvu

Patched: same harness, KASAN silent, the handler returns -EINVAL
at the new gate and never queues the entry; KUnit reports
"ok 1 otx2_rep_event_pcifunc_oob_demux_mac".

Regression: legitimate body pcifunc inside [0, total_pfs) is
unchanged in behaviour and continues to queue and execute on the
same code path; the gate only fires on out-of-range selectors.

Mitigations: none on the VF mailbox path.  Operators who do not
provision SR-IOV VFs in switchdev representor mode are not
exposed.

The KUnit harness module is held off-list and is available on
maintainer request.

 drivers/net/ethernet/marvell/octeontx2/af/rvu.c     | 2 +-
 drivers/net/ethernet/marvell/octeontx2/af/rvu.h     | 1 +
 drivers/net/ethernet/marvell/octeontx2/af/rvu_rep.c | 8 ++++++++
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
index e40b79076358d..3cf131508ecfe 100644
--- a/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
+++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
@@ -436,7 +436,7 @@ struct rvu_pfvf *rvu_get_pfvf(struct rvu *rvu, int pcifunc)
 		return &rvu->pf[rvu_get_pf(rvu->pdev, pcifunc)];
 }
 
-static bool is_pf_func_valid(struct rvu *rvu, u16 pcifunc)
+bool is_pf_func_valid(struct rvu *rvu, u16 pcifunc)
 {
 	int pf, vf, nvfs;
 	u64 cfg;
diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu.h b/drivers/net/ethernet/marvell/octeontx2/af/rvu.h
index a466181cf9082..de3fbd3d15d60 100644
--- a/drivers/net/ethernet/marvell/octeontx2/af/rvu.h
+++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu.h
@@ -917,6 +917,7 @@ u16 rvu_get_rsrc_mapcount(struct rvu_pfvf *pfvf, int blkaddr);
 struct rvu_pfvf *rvu_get_pfvf(struct rvu *rvu, int pcifunc);
 void rvu_get_pf_numvfs(struct rvu *rvu, int pf, int *numvfs, int *hwvf);
 bool is_block_implemented(struct rvu_hwinfo *hw, int blkaddr);
+bool is_pf_func_valid(struct rvu *rvu, u16 pcifunc);
 bool is_pffunc_map_valid(struct rvu *rvu, u16 pcifunc, int blktype);
 int rvu_get_lf(struct rvu *rvu, struct rvu_block *block, u16 pcifunc, u16 slot);
 int rvu_lf_reset(struct rvu *rvu, struct rvu_block *block, int lf);
diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_rep.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu_rep.c
index 901f6fd40fd49..a2781e0f504e3 100644
--- a/drivers/net/ethernet/marvell/octeontx2/af/rvu_rep.c
+++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu_rep.c
@@ -97,6 +97,14 @@ int rvu_mbox_handler_rep_event_notify(struct rvu *rvu, struct rep_event *req,
 {
 	struct rep_evtq_ent *qentry;
 
+	/* The mailbox dispatcher normalises only the header pcifunc; the
+	 * nested struct rep_event::pcifunc body field is sender-controlled
+	 * and is later used by rvu_rep_up_notify() to index rvu->pf[] /
+	 * rvu->hwvf[].  Reject out-of-range body selectors before queueing.
+	 */
+	if (!is_pf_func_valid(rvu, req->pcifunc))
+		return -EINVAL;
+
 	qentry = kmalloc_obj(*qentry, GFP_ATOMIC);
 	if (!qentry)
 		return -ENOMEM;

base-commit: 5200f5f493f79f14bbdc349e402a40dfb32f23c8
-- 
2.53.0