Patch "ACPI: APEI / ERST: Fix missing error handling in erst_reader()" has been added to the 4.14-stable tree

Patch "ACPI: APEI / ERST: Fix missing error handling in erst_reader()" has been added to the 4.14-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    ACPI: APEI / ERST: Fix missing error handling in erst_reader()

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     acpi-apei-erst-fix-missing-error-handling-in-erst_reader.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From bb82e0b4a7e96494f0c1004ce50cec3d7b5fb3d1 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Thu, 14 Dec 2017 13:31:16 +0100
Subject: ACPI: APEI / ERST: Fix missing error handling in erst_reader()

From: Takashi Iwai <tiwai@suse.de>

commit bb82e0b4a7e96494f0c1004ce50cec3d7b5fb3d1 upstream.

The commit f6f828513290 ("pstore: pass allocated memory region back to
caller") changed the check of the return value from erst_read() in
erst_reader() in the following way:

        if (len == -ENOENT)
                goto skip;
-       else if (len < 0) {
-               rc = -1;
+       else if (len < sizeof(*rcd)) {
+               rc = -EIO;
                goto out;

This introduced another bug: since the comparison with sizeof() is
cast to unsigned, a negative len value doesn't hit any longer.
As a result, when an error is returned from erst_read(), the code
falls through, and it may eventually lead to some weird thing like
memory corruption.

This patch adds the negative error value check more explicitly for
addressing the issue.

Fixes: f6f828513290 (pstore: pass allocated memory region back to caller)
Tested-by: Jerry Tang <jtang@suse.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/acpi/apei/erst.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/acpi/apei/erst.c
+++ b/drivers/acpi/apei/erst.c
@@ -1007,7 +1007,7 @@ skip:
 	/* The record may be cleared by others, try read next record */
 	if (len == -ENOENT)
 		goto skip;
-	else if (len < sizeof(*rcd)) {
+	else if (len < 0 || len < sizeof(*rcd)) {
 		rc = -EIO;
 		goto out;
 	}


Patches currently in stable-queue which might be from tiwai@suse.de are

queue-4.14/alsa-usb-audio-fix-the-missing-ctl-name-suffix-at-parsing-su.patch
queue-4.14/alsa-hda-add-vendor-id-for-cannonlake-hdmi-codec.patch
queue-4.14/alsa-rawmidi-avoid-racy-info-ioctl-via-ctl-device.patch
queue-4.14/alsa-usb-audio-add-native-dsd-support-for-esoteric-d-05x.patch
queue-4.14/acpi-apei-erst-fix-missing-error-handling-in-erst_reader.patch
queue-4.14/alsa-hda-realtek-fix-dell-aio-lineout-issue.patch