git: 61b426a0b6a8 - stable/12 - geom_part: Check number of GPT entries and size of GPT entry

The branch stable/12 has been updated by zlei:

URL: https://cgit.FreeBSD.org/src/commit/?id=61b426a0b6a822c6281016a23f28443bb26b891f

commit 61b426a0b6a822c6281016a23f28443bb26b891f
Author:     Zhenlei Huang <zlei.huang@gmail.com>
AuthorDate: 2022-10-18 15:03:02 +0000
Commit:     Zhenlei Huang <zlei@FreeBSD.org>
CommitDate: 2023-09-06 04:32:56 +0000

    geom_part: Check number of GPT entries and size of GPT entry
    
    Current specification does not have upper limit of the number of
    partition entries and the size of partition entry. In
    799eac8c3df597179bbb3b078362f3ff03993a1a Andrey V. Elsukov introduced a
    limit maximum number of GPT entries to 4k, but that is for write routine
    (gpart create) only. When attaching disks that have large number of GPT
    entries exceeding the limit, or disks with large size of partition
    entry, it is still possible to exhaust kernel memory.
    
    1. Reuse the limit of the maximum number of partition entries.
    2. Limit the maximum size of GPT entry to 1k.
    
    In current specification (2.10) the size of GPT entry is 128 *
    2^n while n >= 0, and the size - 128 is reserved. 1k should be
    sufficient enough for foreseen future.
    
    PR:             266548
    Discussed with: imp
    Reviewed by:    markj
    MFC after:      1 month
    Differential Revision:  https://reviews.freebsd.org/D36717
    
    (cherry picked from commit 5be5d0d5cb2657d7668f4ca0f8543198cf8d759b)
    (cherry picked from commit e8c769b22d42fd66d0916e2a04af32ad9d306db1)
---
 sys/geom/part/g_part_gpt.c | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/sys/geom/part/g_part_gpt.c b/sys/geom/part/g_part_gpt.c
index 3d2fb313962f..f0890fd71cd0 100644
--- a/sys/geom/part/g_part_gpt.c
+++ b/sys/geom/part/g_part_gpt.c
@@ -84,6 +84,7 @@ enum gpt_state {
 	GPT_STATE_MISSING,	/* No signature found. */
 	GPT_STATE_CORRUPT,	/* Checksum mismatch. */
 	GPT_STATE_INVALID,	/* Nonconformant/invalid. */
+	GPT_STATE_UNSUPPORTED,  /* Not supported. */
 	GPT_STATE_OK		/* Perfectly fine. */
 };
 
@@ -147,6 +148,8 @@ static kobj_method_t g_part_gpt_methods[] = {
 	{ 0, 0 }
 };
 
+#define MAXENTSIZE 1024
+
 static struct g_part_scheme g_part_gpt_scheme = {
 	"GPT",
 	g_part_gpt_methods,
@@ -525,6 +528,11 @@ gpt_read_tbl(struct g_part_gpt_table *table, struct g_consumer *cp,
 
 	if (hdr == NULL)
 		return (NULL);
+	if (hdr->hdr_entries > g_part_gpt_scheme.gps_maxent ||
+	    hdr->hdr_entsz > MAXENTSIZE) {
+		table->state[elt] = GPT_STATE_UNSUPPORTED;
+		return (NULL);
+	}
 
 	pp = cp->provider;
 	table->lba[elt] = hdr->hdr_lba_table;
@@ -932,10 +940,25 @@ g_part_gpt_read(struct g_part_table *basetable, struct g_consumer *cp)
 	/* Fail if we haven't got any good tables at all. */
 	if (table->state[GPT_ELT_PRITBL] != GPT_STATE_OK &&
 	    table->state[GPT_ELT_SECTBL] != GPT_STATE_OK) {
-		printf("GEOM: %s: corrupt or invalid GPT detected.\n",
-		    pp->name);
-		printf("GEOM: %s: GPT rejected -- may not be recoverable.\n",
-		    pp->name);
+		if (table->state[GPT_ELT_PRITBL] == GPT_STATE_UNSUPPORTED &&
+		    table->state[GPT_ELT_SECTBL] == GPT_STATE_UNSUPPORTED &&
+		    gpt_matched_hdrs(prihdr, sechdr)) {
+			printf("GEOM: %s: unsupported GPT detected.\n",
+			    pp->name);
+			printf(
+		    "GEOM: %s: number of GPT entries: %u, entry size: %uB.\n",
+			    pp->name, prihdr->hdr_entries, prihdr->hdr_entsz);
+			printf(
+    "GEOM: %s: maximum supported number of GPT entries: %u, entry size: %uB.\n",
+			    pp->name, g_part_gpt_scheme.gps_maxent, MAXENTSIZE);
+			printf("GEOM: %s: GPT rejected.\n", pp->name);
+		} else {
+			printf("GEOM: %s: corrupt or invalid GPT detected.\n",
+			    pp->name);
+			printf(
+		    "GEOM: %s: GPT rejected -- may not be recoverable.\n",
+			    pp->name);
+		}
 		if (prihdr != NULL)
 			g_free(prihdr);
 		if (pritbl != NULL)