[PATCH v8 18/26] ACPI / APEI: Make GHES estatus header validation more user friendly

From: James Morse <james.morse@arm.com>
To: linux-acpi@vger.kernel.org
Cc: Rafael Wysocki <rjw@rjwysocki.net>,
	Tony Luck <tony.luck@intel.com>, Xie XiuQi <xiexiuqi@huawei.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>,
	Dongjiu Geng <gengdongjiu@huawei.com>,
	linux-mm@kvack.org, Borislav Petkov <bp@alien8.de>,
	james.morse@arm.com, Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org, Len Brown <lenb@kernel.org>
Subject: [PATCH v8 18/26] ACPI / APEI: Make GHES estatus header validation more user friendly
Date: Tue, 29 Jan 2019 18:48:54 +0000	[thread overview]
Message-ID: <20190129184902.102850-19-james.morse@arm.com> (raw)
In-Reply-To: <20190129184902.102850-1-james.morse@arm.com>

ghes_read_estatus() checks various lengths in the top-level header to
ensure the CPER records to be read aren't obviously corrupt.

Take the opportunity to make this more user-friendly, printing a
(ratelimited) message about the nature of the header format error.

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: James Morse <james.morse@arm.com>
---
 drivers/acpi/apei/ghes.c | 46 ++++++++++++++++++++++++++++------------
 1 file changed, 32 insertions(+), 14 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index f95db2398dd5..9391fff71344 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -293,6 +293,30 @@ static void ghes_copy_tofrom_phys(void *buffer, u64 paddr, u32 len,
 	}
 }
 
+/* Check the top-level record header has an appropriate size. */
+int __ghes_check_estatus(struct ghes *ghes,
+			 struct acpi_hest_generic_status *estatus)
+{
+	u32 len = cper_estatus_len(estatus);
+
+	if (len < sizeof(*estatus)) {
+		pr_warn_ratelimited(FW_WARN GHES_PFX "Truncated error status block!\n");
+		return -EIO;
+	}
+
+	if (len > ghes->generic->error_block_length) {
+		pr_warn_ratelimited(FW_WARN GHES_PFX "Invalid error status block length!\n");
+		return -EIO;
+	}
+
+	if (cper_estatus_check_header(estatus)) {
+		pr_warn_ratelimited(FW_WARN GHES_PFX "Invalid CPER header!\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
 static int ghes_read_estatus(struct ghes *ghes,
 			     struct acpi_hest_generic_status *estatus,
 			     u64 *buf_paddr, enum fixed_addresses fixmap_idx)
@@ -319,27 +343,21 @@ static int ghes_read_estatus(struct ghes *ghes,
 		return -ENOENT;
 	}
 
-	rc = -EIO;
+	rc = __ghes_check_estatus(ghes, estatus);
+	if (rc)
+		return rc;
+
 	len = cper_estatus_len(estatus);
-	if (len < sizeof(*estatus))
-		goto err_read_block;
-	if (len > ghes->generic->error_block_length)
-		goto err_read_block;
-	if (cper_estatus_check_header(estatus))
-		goto err_read_block;
 	ghes_copy_tofrom_phys(estatus + 1,
 			      *buf_paddr + sizeof(*estatus),
 			      len - sizeof(*estatus), 1, fixmap_idx);
-	if (cper_estatus_check(estatus))
-		goto err_read_block;
-	rc = 0;
-
-err_read_block:
-	if (rc)
+	if (cper_estatus_check(estatus)) {
 		pr_warn_ratelimited(FW_WARN GHES_PFX
 				    "Failed to read error status block!\n");
+		return -EIO;
+	}
 
-	return rc;
+	return 0;
 }
 
 static void ghes_clear_estatus(struct ghes *ghes,
-- 
2.20.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
