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From: "Krzysztof Koch" <krzysztof.koch@arm.com>
To: <devel@edk2.groups.io>
Cc: <ray.ni@intel.com>, <zhichao.gao@intel.com>,
	<Sami.Mujawar@arm.com>, <Matteo.Carlini@arm.com>, <nd@arm.com>
Subject: [PATCH v3 01/11] ShellPkg: acpiview: Set ItemPtr to NULL for unprocessed table fields
Date: Mon, 20 Jan 2020 11:13:41 +0000	[thread overview]
Message-ID: <20200120111351.29184-2-krzysztof.koch@arm.com> (raw)
In-Reply-To: <20200120111351.29184-1-krzysztof.koch@arm.com>

For fields outside the buffer length provided, reset any pointers,
which were supposed to be updated by a ParseAcpi() function call to
NULL. This way one can easily validate if a pointer was successfully
updated.

The ParseAcpi() function parses the given ACPI table buffer by a
number of bytes which is a minimum of the buffer length and the length
described by ACPI_PARSER array. If the buffer length is shorter than
the array describing how to process the ACPI structure, then it is
possible that the ItemPtr inside ACPI_PARSER may not get updated or
initialized. This can lead to an error if the value pointed to by
ItemPtr is later used to control the parsing logic.

A typical example would be a 'number of elements' field in an ACPI
structure header which defines how many substructures of a given type
are present in the structure body. If the 'number of elements' field
is not parsed, we will have a dangling pointer which could cause a
problem later.

Signed-off-by: Krzysztof Koch <krzysztof.koch@arm.com>
---

Notes:
    v3:
    - Rebase on latest master [Krzysztof]

    v1:
    - Set ItemPtr to NULL for unprocessed table fields [Krzysztof]

 ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c
index 2b2ecb93cef9ee28b752e7bf2d920b059dbf7d6b..84c5f0468da55477acc96dfd0f949a5908d0f7a5 100644
--- a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c
+++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c
@@ -543,8 +543,15 @@ ParseAcpi (
 
   for (Index = 0; Index < ParserItems; Index++) {
     if ((Offset + Parser[Index].Length) > Length) {
+
+      // For fields outside the buffer length provided, reset any pointers
+      // which were supposed to be updated by this function call
+      if (Parser[Index].ItemPtr != NULL) {
+        *Parser[Index].ItemPtr = NULL;
+      }
+
       // We don't parse past the end of the max length specified
-      break;
+      continue;
     }
 
     if (GetConsistencyChecking () &&
--
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'



  reply	other threads:[~2020-01-20 11:14 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-20 11:13 [PATCH v3 00/11] Test against invalid pointers in acpiview Krzysztof Koch
2020-01-20 11:13 ` Krzysztof Koch [this message]
2020-01-20 11:13 ` [PATCH v3 02/11] ShellPkg: acpiview: RSDP: Validate global pointer before use Krzysztof Koch
2020-01-20 11:13 ` [PATCH v3 03/11] ShellPkg: acpiview: FADT: " Krzysztof Koch
2020-01-20 11:13 ` [PATCH v3 04/11] ShellPkg: acpiview: SLIT: " Krzysztof Koch
2020-01-20 11:13 ` [PATCH v3 05/11] ShellPkg: acpiview: SLIT: Validate System Locality count Krzysztof Koch
2020-01-20 11:13 ` [PATCH v3 06/11] ShellPkg: acpiview: SRAT: Validate global pointers before use Krzysztof Koch
2020-01-20 11:13 ` [PATCH v3 07/11] ShellPkg: acpiview: MADT: " Krzysztof Koch
2020-01-20 11:13 ` [PATCH v3 08/11] ShellPkg: acpiview: PPTT: " Krzysztof Koch
2020-01-20 11:13 ` [PATCH v3 09/11] ShellPkg: acpiview: IORT: " Krzysztof Koch
2020-01-20 11:13 ` [PATCH v3 10/11] ShellPkg: acpiview: GTDT: " Krzysztof Koch
2020-01-20 11:13 ` [PATCH v3 11/11] ShellPkg: acpiview: DBG2: " Krzysztof Koch
2020-02-03 15:36 ` [PATCH v3 00/11] Test against invalid pointers in acpiview Gao, Zhichao

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