[GIT PULL] x86 fixes

Ingo Molnar
2018-10-11T09:14:23Z

Greg,

Please pull the latest x86-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-urgent-for-linus

# HEAD: 184d47f0fd365108bd06ab26cdb3450b716269fd x86/mm: Avoid VLA in pgd_alloc()

An intel_rdt memory access fix and a VLA fix in pgd_alloc().

Thanks,

Ingo

------------------>
Kees Cook (1):
x86/mm: Avoid VLA in pgd_alloc()

Reinette Chatre (1):
x86/intel_rdt: Fix out-of-bounds memory access in CBM tests

arch/x86/kernel/cpu/intel_rdt.h | 6 ++---
arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c | 20 ++++++++--------
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 36 ++++++++++++++++++-----------
arch/x86/mm/pgtable.c | 10 ++++++--
4 files changed, 45 insertions(+), 27 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel_rdt.h b/arch/x86/kernel/cpu/intel_rdt.h
index 285eb3ec4200..3736f6dc9545 100644
--- a/arch/x86/kernel/cpu/intel_rdt.h
+++ b/arch/x86/kernel/cpu/intel_rdt.h
@@ -529,14 +529,14 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
int rdtgroup_schemata_show(struct kernfs_open_file *of,
struct seq_file *s, void *v);
bool rdtgroup_cbm_overlaps(struct rdt_resource *r, struct rdt_domain *d,
- u32 _cbm, int closid, bool exclusive);
+ unsigned long cbm, int closid, bool exclusive);
unsigned int rdtgroup_cbm_to_size(struct rdt_resource *r, struct rdt_domain *d,
- u32 cbm);
+ unsigned long cbm);
enum rdtgrp_mode rdtgroup_mode_by_closid(int closid);
int rdtgroup_tasks_assigned(struct rdtgroup *r);
int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);
int rdtgroup_locksetup_exit(struct rdtgroup *rdtgrp);
-bool rdtgroup_cbm_overlaps_pseudo_locked(struct rdt_domain *d, u32 _cbm);
+bool rdtgroup_cbm_overlaps_pseudo_locked(struct rdt_domain *d, unsigned long cbm);
bool rdtgroup_pseudo_locked_in_hierarchy(struct rdt_domain *d);
int rdt_pseudo_lock_init(void);
void rdt_pseudo_lock_release(void);
diff --git a/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c b/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c
index 40f3903ae5d9..f8c260d522ca 100644
--- a/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c
+++ b/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c
@@ -797,25 +797,27 @@ int rdtgroup_locksetup_exit(struct rdtgroup *rdtgrp)
/**
* rdtgroup_cbm_overlaps_pseudo_locked - Test if CBM or portion is pseudo-locked
* @d: RDT domain
- * @_cbm: CBM to test
+ * @cbm: CBM to test
*
- * @d represents a cache instance and @_cbm a capacity bitmask that is
- * considered for it. Determine if @_cbm overlaps with any existing
+ * @d represents a cache instance and @cbm a capacity bitmask that is
+ * considered for it. Determine if @cbm overlaps with any existing
* pseudo-locked region on @d.
*
- * Return: true if @_cbm overlaps with pseudo-locked region on @d, false
+ * @cbm is unsigned long, even if only 32 bits are used, to make the
+ * bitmap functions work correctly.
+ *
+ * Return: true if @cbm overlaps with pseudo-locked region on @d, false
* otherwise.
*/
-bool rdtgroup_cbm_overlaps_pseudo_locked(struct rdt_domain *d, u32 _cbm)
+bool rdtgroup_cbm_overlaps_pseudo_locked(struct rdt_domain *d, unsigned long cbm)
{
- unsigned long *cbm = (unsigned long *)&_cbm;
- unsigned long *cbm_b;
unsigned int cbm_len;
+ unsigned long cbm_b;

if (d->plr) {
cbm_len = d->plr->r->cache.cbm_len;
- cbm_b = (unsigned long *)&d->plr->cbm;
- if (bitmap_intersects(cbm, cbm_b, cbm_len))
+ cbm_b = d->plr->cbm;
+ if (bitmap_intersects(&cbm, &cbm_b, cbm_len))
return true;
}
return false;
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 1b8e86a5d5e1..b140c68bc14b 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -975,33 +975,34 @@ static int rdtgroup_mode_show(struct kernfs_open_file *of,
* is false then overlaps with any resource group or hardware entities
* will be considered.
*
+ * @cbm is unsigned long, even if only 32 bits are used, to make the
+ * bitmap functions work correctly.
+ *
* Return: false if CBM does not overlap, true if it does.
*/
bool rdtgroup_cbm_overlaps(struct rdt_resource *r, struct rdt_domain *d,
- u32 _cbm, int closid, bool exclusive)
+ unsigned long cbm, int closid, bool exclusive)
{
- unsigned long *cbm = (unsigned long *)&_cbm;
- unsigned long *ctrl_b;
enum rdtgrp_mode mode;
+ unsigned long ctrl_b;
u32 *ctrl;
int i;

/* Check for any overlap with regions used by hardware directly */
if (!exclusive) {
- if (bitmap_intersects(cbm,
- (unsigned long *)&r->cache.shareable_bits,
- r->cache.cbm_len))
+ ctrl_b = r->cache.shareable_bits;
+ if (bitmap_intersects(&cbm, &ctrl_b, r->cache.cbm_len))
return true;
}

/* Check for overlap with other resource groups */
ctrl = d->ctrl_val;
for (i = 0; i < closids_supported(); i++, ctrl++) {
- ctrl_b = (unsigned long *)ctrl;
+ ctrl_b = *ctrl;
mode = rdtgroup_mode_by_closid(i);
if (closid_allocated(i) && i != closid &&
mode != RDT_MODE_PSEUDO_LOCKSETUP) {
- if (bitmap_intersects(cbm, ctrl_b, r->cache.cbm_len)) {
+ if (bitmap_intersects(&cbm, &ctrl_b, r->cache.cbm_len)) {
if (exclusive) {
if (mode == RDT_MODE_EXCLUSIVE)
return true;
@@ -1138,15 +1139,18 @@ static ssize_t rdtgroup_mode_write(struct kernfs_open_file *of,
* computed by first dividing the total cache size by the CBM length to
* determine how many bytes each bit in the bitmask represents. The result
* is multiplied with the number of bits set in the bitmask.
+ *
+ * @cbm is unsigned long, even if only 32 bits are used to make the
+ * bitmap functions work correctly.
*/
unsigned int rdtgroup_cbm_to_size(struct rdt_resource *r,
- struct rdt_domain *d, u32 cbm)
+ struct rdt_domain *d, unsigned long cbm)
{
struct cpu_cacheinfo *ci;
unsigned int size = 0;
int num_b, i;

- num_b = bitmap_weight((unsigned long *)&cbm, r->cache.cbm_len);
+ num_b = bitmap_weight(&cbm, r->cache.cbm_len);
ci = get_cpu_cacheinfo(cpumask_any(&d->cpu_mask));
for (i = 0; i < ci->num_leaves; i++) {
if (ci->info_list[i].level == r->cache_level) {
@@ -2353,6 +2357,7 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
u32 used_b = 0, unused_b = 0;
u32 closid = rdtgrp->closid;
struct rdt_resource *r;
+ unsigned long tmp_cbm;
enum rdtgrp_mode mode;
struct rdt_domain *d;
int i, ret;
@@ -2390,9 +2395,14 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
* modify the CBM based on system availability.
*/
cbm_ensure_valid(&d->new_ctrl, r);
- if (bitmap_weight((unsigned long *) &d->new_ctrl,
- r->cache.cbm_len) <
- r->cache.min_cbm_bits) {
+ /*
+ * Assign the u32 CBM to an unsigned long to ensure
+ * that bitmap_weight() does not access out-of-bound
+ * memory.
+ */
+ tmp_cbm = d->new_ctrl;
+ if (bitmap_weight(&tmp_cbm, r->cache.cbm_len) <
+ r->cache.min_cbm_bits) {
rdt_last_cmd_printf("no space on %s:%d\n",
r->name, d->id);
return -ENOSPC;
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 089e78c4effd..59274e2c1ac4 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -115,6 +115,8 @@ static inline void pgd_list_del(pgd_t *pgd)

#define UNSHARED_PTRS_PER_PGD \
(SHARED_KERNEL_PMD ? KERNEL_PGD_BOUNDARY : PTRS_PER_PGD)
+#define MAX_UNSHARED_PTRS_PER_PGD \
+ max_t(size_t, KERNEL_PGD_BOUNDARY, PTRS_PER_PGD)

static void pgd_set_mm(pgd_t *pgd, struct mm_struct *mm)
@@ -181,6 +183,7 @@ static void pgd_dtor(pgd_t *pgd)
* and initialize the kernel pmds here.
*/
#define PREALLOCATED_PMDS UNSHARED_PTRS_PER_PGD
+#define MAX_PREALLOCATED_PMDS MAX_UNSHARED_PTRS_PER_PGD

/*
* We allocate separate PMDs for the kernel part of the user page-table
@@ -189,6 +192,7 @@ static void pgd_dtor(pgd_t *pgd)
*/
#define PREALLOCATED_USER_PMDS (static_cpu_has(X86_FEATURE_PTI) ? \
KERNEL_PGD_PTRS : 0)
+#define MAX_PREALLOCATED_USER_PMDS KERNEL_PGD_PTRS

void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd)
{
@@ -210,7 +214,9 @@ void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd)

/* No need to prepopulate any pagetable entries in non-PAE modes. */
#define PREALLOCATED_PMDS 0
+#define MAX_PREALLOCATED_PMDS 0
#define PREALLOCATED_USER_PMDS 0
+#define MAX_PREALLOCATED_USER_PMDS 0
#endif /* CONFIG_X86_PAE */

static void free_pmds(struct mm_struct *mm, pmd_t *pmds[], int count)
@@ -428,8 +434,8 @@ static inline void _pgd_free(pgd_t *pgd)
pgd_t *pgd_alloc(struct mm_struct *mm)
{
pgd_t *pgd;
- pmd_t *u_pmds[PREALLOCATED_USER_PMDS];
- pmd_t *pmds[PREALLOCATED_PMDS];
+ pmd_t *u_pmds[MAX_PREALLOCATED_USER_PMDS];
+ pmd_t *pmds[MAX_PREALLOCATED_PMDS];

pgd = _pgd_alloc();