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 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

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-4.9 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 @@ -1020,7 +1020,7 @@ 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-4.9/alsa-usb-audio-fix-the-missing-ctl-name-suffix-at-parsing-su.patch queue-4.9/alsa-rawmidi-avoid-racy-info-ioctl-via-ctl-device.patch queue-4.9/alsa-usb-audio-add-native-dsd-support-for-esoteric-d-05x.patch queue-4.9/acpi-apei-erst-fix-missing-error-handling-in-erst_reader.patch