[PATCH 32/33] scsi: qla2xxx: Bound i2c->length in I2C bsg handlers

struct qla_i2c_access carries a 16-bit length field alongside a fixed
64-byte buffer:

	struct qla_i2c_access {
		uint16_t device, offset, option, length;
		uint8_t  buffer[0x40];
	} __packed;

qla2x00_write_i2c() and qla2x00_read_i2c() use the user-supplied
i2c->length without any bounds check. i2c is overlaid on a 256-byte
on-stack buffer and sfp is a 256-byte DMA-pool buffer, so a length up to
65535 overruns both:

  - write: memcpy(sfp, i2c->buffer, i2c->length) over-reads the stack and
    over-writes the sfp heap buffer, and qla2x00_write_sfp() then DMAs
    i2c->length bytes out of the 256-byte buffer.
  - read: qla2x00_read_sfp() DMAs i2c->length bytes into the 256-byte sfp,
    then memcpy(i2c->buffer, sfp, i2c->length) overflows the 64-byte
    buffer inside the on-stack array.

A caller holding CAP_SYS_RAWIO can use this to corrupt the heap and the
kernel stack. Reject requests whose length exceeds the buffer before any
copy or DMA transfer in both handlers.

Fixes: 9ebb5d9c69f1 ("[SCSI] qla2xxx: Add I2C BSG interface.")
Cc: [email protected]
Reported-by: Sashiko <[email protected]>
Signed-off-by: Nilesh Javali <[email protected]>
---
 drivers/scsi/qla2xxx/qla_bsg.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/scsi/qla2xxx/qla_bsg.c b/drivers/scsi/qla2xxx/qla_bsg.c
index 59fcc726b682..ab559048dbb8 100644
--- a/drivers/scsi/qla2xxx/qla_bsg.c
+++ b/drivers/scsi/qla2xxx/qla_bsg.c
@@ -2175,6 +2175,12 @@ qla2x00_write_i2c(struct bsg_job *bsg_job)
 	sg_copy_to_buffer(bsg_job->request_payload.sg_list,
 	    bsg_job->request_payload.sg_cnt, i2c, sizeof(*i2c));
 
+	if (i2c->length > sizeof(i2c->buffer)) {
+		bsg_reply->reply_data.vendor_reply.vendor_rsp[0] =
+		    EXT_STATUS_INVALID_PARAM;
+		goto dealloc;
+	}
+
 	memcpy(sfp, i2c->buffer, i2c->length);
 	rval = qla2x00_write_sfp(vha, sfp_dma, sfp,
 	    i2c->device, i2c->offset, i2c->length, i2c->option);
@@ -2221,6 +2227,12 @@ qla2x00_read_i2c(struct bsg_job *bsg_job)
 	sg_copy_to_buffer(bsg_job->request_payload.sg_list,
 	    bsg_job->request_payload.sg_cnt, i2c, sizeof(*i2c));
 
+	if (i2c->length > sizeof(i2c->buffer)) {
+		bsg_reply->reply_data.vendor_reply.vendor_rsp[0] =
+		    EXT_STATUS_INVALID_PARAM;
+		goto dealloc;
+	}
+
 	rval = qla2x00_read_sfp(vha, sfp_dma, sfp,
 		i2c->device, i2c->offset, i2c->length, i2c->option);
 
-- 
2.47.3