From f759546498d820670934c901a2fdf1ce948d2e5c Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Mon, 12 May 2014 01:13:28 +0200 Subject: ACPI / TPM: Fix resume regression on Chromebooks Chromebooks (at least Acer C720 and Pixel) implement an ACPI object for TPM, but don't implement the _DSM method to support PPI. As a result, the TPM driver fails to load on those machines after commit 1569a4c4ceba (ACPI / TPM: detect PPI features by checking availability of _DSM functions) which causes them to fail to resume from system suspend, becuase they require the TPM hardware to be put into the right state during resume and the TPM driver is necessary for that. Fix the problem by making tpm_add_ppi() return 0 when tpm_ppi_handle is still NULL after walking the ACPI namespace in search for the PPI _DSM, which allows the TPM driver to load and operate the hardware (during system resume in particular), but avoid creating the PPI sysfs group in that case. This change is based on a prototype patch from Jiang Liu. Fixes: 1569a4c4ceba (ACPI / TPM: detect PPI features by checking availability of _DSM functions) References: https://bugzilla.kernel.org/show_bug.cgi?id=74021 Reported-by: James Duley Reported-by: Phillip Dixon Tested-by: Brandon Casey Cc: 3.14+ # 3.14+ Signed-off-by: Rafael J. Wysocki --- drivers/char/tpm/tpm_ppi.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) (limited to 'drivers/char') diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c index b3ea223585bd..61dcc8011ec7 100644 --- a/drivers/char/tpm/tpm_ppi.c +++ b/drivers/char/tpm/tpm_ppi.c @@ -328,13 +328,11 @@ int tpm_add_ppi(struct kobject *parent) /* Cache TPM ACPI handle and version string */ acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT, ACPI_UINT32_MAX, ppi_callback, NULL, NULL, &tpm_ppi_handle); - if (tpm_ppi_handle == NULL) - return -ENODEV; - - return sysfs_create_group(parent, &ppi_attr_grp); + return tpm_ppi_handle ? sysfs_create_group(parent, &ppi_attr_grp) : 0; } void tpm_remove_ppi(struct kobject *parent) { - sysfs_remove_group(parent, &ppi_attr_grp); + if (tpm_ppi_handle) + sysfs_remove_group(parent, &ppi_attr_grp); } -- cgit v1.2.3 From f9c6d4987b23e0a514464bae6771933a48e4cd01 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Fri, 16 May 2014 21:40:41 -0400 Subject: random: fix BUG_ON caused by accounting simplification Commit ee1de406ba6eb1 ("random: simplify accounting logic") simplified things too much, in that it allows the following to trigger an overflow that results in a BUG_ON crash: dd if=/dev/urandom of=/dev/zero bs=67108707 count=1 Thanks to Peter Zihlstra for discovering the crash, and Hannes Frederic for analyizing the root cause. Signed-off-by: "Theodore Ts'o" Reported-by: Peter Zijlstra Reported-by: Hannes Frederic Sowa Cc: Greg Price --- drivers/char/random.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'drivers/char') diff --git a/drivers/char/random.c b/drivers/char/random.c index 6b75713d953a..102c50d38902 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -995,8 +995,11 @@ retry: ibytes = min_t(size_t, ibytes, have_bytes - reserved); if (ibytes < min) ibytes = 0; - entropy_count = max_t(int, 0, - entropy_count - (ibytes << (ENTROPY_SHIFT + 3))); + if (have_bytes >= ibytes + reserved) + entropy_count -= ibytes << (ENTROPY_SHIFT + 3); + else + entropy_count = reserved << (ENTROPY_SHIFT + 3); + if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) goto retry; -- cgit v1.2.3