[PATCH V2] ieee1275/ofdisk: vscsi lun handling on lun len

From: Mukesh Kumar Chaurasiya <mchauras@linux.ibm.com>
To: grub-devel@gnu.org
Cc: meghanaprakash@in.ibm.com, avnish@linux.vnet.ibm.com,
	brking@linux.vnet.ibm.com, mamatha4@linux.vnet.ibm.com,
	mchauras@linux.vnet.ibm.com,
	Mukesh Kumar Chaurasiya <mchauras@linux.ibm.com>
Subject: [PATCH V2] ieee1275/ofdisk: vscsi lun handling on lun len
Date: Mon, 27 Nov 2023 18:07:42 +0530	[thread overview]
Message-ID: <20231127123740.109635-3-mchauras@linux.ibm.com> (raw)

The information about "vscsi-report-luns" data is a list of disk details
with pairs of memory addresses and lengths.

                  8 bytes     8 bytes
lun-addr  --->   ------------------------              8 bytes
        ^        |  buf-addr |  buf-len | --------> -------------
        |        ------------------------           |   lun     |
        |        |  buf-addr |  buf-len | ----|     -------------
     "len"       ------------------------     |     |  ...      |
        |        |    ...               |     |     -------------
        |        ------------------------     |     |   lun     |
        |        |  buf-addr |  buf-len |     |     -------------
        V        ------------------------     |
                                              |---> -------------
                                                    |   lun     |
                                                    -------------
                                                    |  ...      |
                                                    -------------
                                                    |   lun     |
                                                    -------------
The way the expression "(args.table + 4 + 8 * i)" is used is incorrect and
can be confusing. The list of LUNs doesn't end with NULL, indicated by
"while (*ptr)". Usually, this loop doesn't process any LUNs because it ends
before checking any as first reported LUN is likely to be "0". The list of
LUNs ends based on its length, not by a NULL value.

Signed-off-by: Mukesh Kumar Chaurasiya <mchauras@linux.ibm.com>
---
 grub-core/disk/ieee1275/ofdisk.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/grub-core/disk/ieee1275/ofdisk.c b/grub-core/disk/ieee1275/ofdisk.c
index c6cba0c8a..9cd8898f1 100644
--- a/grub-core/disk/ieee1275/ofdisk.c
+++ b/grub-core/disk/ieee1275/ofdisk.c
@@ -222,8 +222,12 @@ dev_iterate (const struct grub_ieee1275_devalias *alias)
 	grub_ieee1275_cell_t table;
       }
       args;
+      struct lun_buf {
+	grub_uint64_t *buf_addr;
+	grub_uint64_t buf_len;
+      } *tbl;
       char *buf, *bufptr;
-      unsigned i;
+      unsigned int i, j;
 
       if (grub_ieee1275_open (alias->path, &ihandle))
 	return;
@@ -248,12 +252,13 @@ dev_iterate (const struct grub_ieee1275_devalias *alias)
 	return;
       bufptr = grub_stpcpy (buf, alias->path);
 
+      tbl = (struct lun_len *) args.table;
       for (i = 0; i < args.nentries; i++)
 	{
 	  grub_uint64_t *ptr;
 
-	  ptr = *(grub_uint64_t **) (args.table + 4 + 8 * i);
-	  while (*ptr)
+	  ptr = (grub_uint64_t *)(grub_addr_t) tbl[i].buf_addr;
+	  for (j = 0; j < tbl[i].buf_len; j++)
 	    {
 	      grub_snprintf (bufptr, 32, "/disk@%" PRIxGRUB_UINT64_T, *ptr++);
 	      dev_iterate_real (buf, buf);
-- 
2.43.0


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