linux-kernel - [PATCH 48/49] ACPI: Harden acpi_table_parse

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat,  6 Oct 2012 22:43:18 -0400
From:	Len Brown <lenb@...nel.org>
To:	linux-acpi@...r.kernel.org, linux-pm@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Fenghua Yu <fenghua.yu@...el.com>,
	Len Brown <len.brown@...el.com>
Subject: [PATCH 48/49] ACPI: Harden acpi_table_parse_entries() against BIOS bug

From: Fenghua Yu <fenghua.yu@...el.com>

Parsing acpi table entries may fall into an infinite loop on a buggy BIOS
which has entry length=0 in acpi table.

Instead of kernel hang with few failure clue which leads to heavy lifting debug
effort, this patch hardens kernel boot by booting into non NUMA mode. The debug
info left in log buffer helps people identify the issue.

Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
Signed-off-by: Len Brown <len.brown@...el.com>
---
 drivers/acpi/tables.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index f336bca7..2572d97 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -240,10 +240,17 @@ acpi_table_parse_entries(char *id,
 	       table_end) {
 		if (entry->type == entry_id
 		    && (!max_entries || count++ < max_entries))
-			if (handler(entry, table_end)) {
-				early_acpi_os_unmap_memory((char *)table_header, tbl_size);
-				return -EINVAL;
-			}
+			if (handler(entry, table_end))
+				goto err;
+
+		/*
+		 * If entry->length is 0, break from this loop to avoid
+		 * infinite loop.
+		 */
+		if (entry->length == 0) {
+			pr_err(PREFIX "[%4.4s:0x%02x] Invalid zero length\n", id, entry_id);
+			goto err;
+		}
 
 		entry = (struct acpi_subtable_header *)
 		    ((unsigned long)entry + entry->length);
@@ -255,6 +262,9 @@ acpi_table_parse_entries(char *id,
 
 	early_acpi_os_unmap_memory((char *)table_header, tbl_size);
 	return count;
+err:
+	early_acpi_os_unmap_memory((char *)table_header, tbl_size);
+	return -EINVAL;
 }
 
 int __init
-- 
1.8.0.rc0.18.gf84667d

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/