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SubjectRe: [PATCH 3/3] vdso: preallocate new vmas
From
Date
From: Davidlohr Bueso <davidlohr@hp.com>
Subject: [PATCH v2 3/3] vdso: preallocate new vmas

With the exception of um and tile, architectures that use
the install_special_mapping() function, when setting up a
new vma at program startup, do so with the mmap_sem lock
held for writing. Unless there's an error, this process
ends up allocating a new vma through kmem_cache_zalloc,
and inserting it in the task's address space.

This patch moves the vma's space allocation outside of
install_special_mapping(), and leaves the callers to do so
explicitly, without depending on mmap_sem. The same goes for
freeing: if the new vma isn't used (and thus the process fails
at some point), it's caller's responsibility to free it -
currently this is done inside install_special_mapping.

Furthermore, uprobes behaves exactly the same and thus now the
xol_add_vma() function also preallocates the new vma.

While the changes to x86 vdso handling have been tested on both
large and small 64-bit systems, the rest of the architectures
are totally *untested*. Note that all changes are quite similar
from architecture to architecture.

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
v2:
- Simplify install_special_mapping interface (Linus Torvalds)
- Fix return for uml_setup_stubs when mem allocation fails (Richard Weinberger)

arch/arm/kernel/process.c | 22 ++++++++++++++++------
arch/arm64/kernel/vdso.c | 21 +++++++++++++++++----
arch/hexagon/kernel/vdso.c | 16 ++++++++++++----
arch/mips/kernel/vdso.c | 10 +++++++++-
arch/powerpc/kernel/vdso.c | 11 ++++++++---
arch/s390/kernel/vdso.c | 19 +++++++++++++++----
arch/sh/kernel/vsyscall/vsyscall.c | 11 ++++++++++-
arch/tile/kernel/vdso.c | 13 ++++++++++---
arch/um/kernel/skas/mmu.c | 16 +++++++++++-----
arch/unicore32/kernel/process.c | 17 ++++++++++++-----
arch/x86/um/vdso/vma.c | 18 ++++++++++++++----
arch/x86/vdso/vdso32-setup.c | 16 +++++++++++++++-
arch/x86/vdso/vma.c | 10 +++++++++-
include/linux/mm.h | 3 ++-
kernel/events/uprobes.c | 14 ++++++++++++--
mm/mmap.c | 17 ++++++-----------
16 files changed, 178 insertions(+), 56 deletions(-)

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 94f6b05..d1eb115 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -13,6 +13,7 @@
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/kernel.h>
+#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
@@ -480,6 +481,7 @@ extern struct page *get_signal_page(void);
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
unsigned long addr;
int ret;

@@ -488,6 +490,10 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
if (!signal_page)
return -ENOMEM;

+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return -ENOMEM;
+
down_write(&mm->mmap_sem);
addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
if (IS_ERR_VALUE(addr)) {
@@ -496,14 +502,18 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
}

ret = install_special_mapping(mm, addr, PAGE_SIZE,
- VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
- &signal_page);
-
- if (ret == 0)
- mm->context.sigpage = addr;
+ VM_READ | VM_EXEC | VM_MAYREAD |
+ VM_MAYWRITE | VM_MAYEXEC,
+ &signal_page, vma);
+ if (ret)
+ goto up_fail;

- up_fail:
+ mm->context.sigpage = addr;
+ up_write(&mm->mmap_sem);
+ return 0;
+up_fail:
up_write(&mm->mmap_sem);
+ kmem_cache_free(vm_area_cachep, vma);
return ret;
}
#endif
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 6a389dc..06a01ea 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -83,20 +83,26 @@ arch_initcall(alloc_vectors_page);

int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
{
+ struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
unsigned long addr = AARCH32_VECTORS_BASE;
int ret;

+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return -ENOMEM;
+
down_write(&mm->mmap_sem);
current->mm->context.vdso = (void *)addr;

/* Map vectors page at the high address. */
ret = install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC,
- vectors_page);
+ vectors_page, vma);

up_write(&mm->mmap_sem);
-
+ if (ret)
+ kmem_cache_free(vm_area_cachep, vma);
return ret;
}
#endif /* CONFIG_COMPAT */
@@ -152,10 +158,15 @@ arch_initcall(vdso_init);
int arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp)
{
+ struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
unsigned long vdso_base, vdso_mapping_len;
int ret;

+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return -ENOMEM;
+
/* Be sure to map the data page */
vdso_mapping_len = (vdso_pages + 1) << PAGE_SHIFT;

@@ -170,15 +181,17 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
ret = install_special_mapping(mm, vdso_base, vdso_mapping_len,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- vdso_pagelist);
+ vdso_pagelist, vma);
if (ret) {
mm->context.vdso = NULL;
goto up_fail;
}

+ up_write(&mm->mmap_sem);
+ return ret;
up_fail:
up_write(&mm->mmap_sem);
-
+ kmem_cache_free(vm_area_cachep, vma);
return ret;
}

diff --git a/arch/hexagon/kernel/vdso.c b/arch/hexagon/kernel/vdso.c
index 0bf5a87..418a896 100644
--- a/arch/hexagon/kernel/vdso.c
+++ b/arch/hexagon/kernel/vdso.c
@@ -19,6 +19,7 @@
*/

#include <linux/err.h>
+#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/binfmts.h>
@@ -63,8 +64,13 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
int ret;
unsigned long vdso_base;
+ struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;

+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return -ENOMEM;
+
down_write(&mm->mmap_sem);

/* Try to get it loaded right near ld.so/glibc. */
@@ -78,17 +84,19 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)

/* MAYWRITE to allow gdb to COW and set breakpoints. */
ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
- VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- &vdso_page);
-
+ VM_READ|VM_EXEC|
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+ &vdso_page, vma);
if (ret)
goto up_fail;

mm->context.vdso = (void *)vdso_base;

+ up_write(&mm->mmap_sem);
+ return 0;
up_fail:
up_write(&mm->mmap_sem);
+ kmem_cache_free(vm_area_cachep, vma);
return ret;
}

diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c
index 0f1af58..fb44fc9 100644
--- a/arch/mips/kernel/vdso.c
+++ b/arch/mips/kernel/vdso.c
@@ -74,8 +74,13 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
int ret;
unsigned long addr;
+ struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;

+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return -ENOMEM;
+
down_write(&mm->mmap_sem);

addr = vdso_addr(mm->start_stack);
@@ -89,15 +94,18 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
ret = install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- &vdso_page);
+ &vdso_page, vma);

if (ret)
goto up_fail;

mm->context.vdso = (void *)addr;

+ up_write(&mm->mmap_sem);
+ return 0;
up_fail:
up_write(&mm->mmap_sem);
+ kmem_cache_free(vm_area_cachep, vma);
return ret;
}

diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 1d9c926..ed339de 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -193,6 +193,7 @@ static void dump_vdso_pages(struct vm_area_struct * vma)
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
struct page **vdso_pagelist;
unsigned long vdso_pages;
unsigned long vdso_base;
@@ -232,6 +233,10 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
/* Add a page to the vdso size for the data page */
vdso_pages ++;

+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return -ENOMEM;
+
/*
* pick a base address for the vDSO in process space. We try to put it
* at vdso_base which is the "natural" base for it, but we might fail
@@ -271,7 +276,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- vdso_pagelist);
+ vdso_pagelist, vma);
if (rc) {
current->mm->context.vdso_base = 0;
goto fail_mmapsem;
@@ -279,9 +284,9 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)

up_write(&mm->mmap_sem);
return 0;
-
- fail_mmapsem:
+fail_mmapsem:
up_write(&mm->mmap_sem);
+ kmem_cache_free(vm_area_cachep, vma);
return rc;
}

diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
index 05d75c4..e2a707d 100644
--- a/arch/s390/kernel/vdso.c
+++ b/arch/s390/kernel/vdso.c
@@ -180,6 +180,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
struct page **vdso_pagelist;
+ struct vm_area_struct *vma;
unsigned long vdso_pages;
unsigned long vdso_base;
int rc;
@@ -213,6 +214,10 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
if (vdso_pages == 0)
return 0;

+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return -ENOMEM;
+
current->mm->context.vdso_base = 0;

/*
@@ -224,7 +229,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
vdso_base = get_unmapped_area(NULL, 0, vdso_pages << PAGE_SHIFT, 0, 0);
if (IS_ERR_VALUE(vdso_base)) {
rc = vdso_base;
- goto out_up;
+ goto out_err;
}

/*
@@ -247,11 +252,17 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- vdso_pagelist);
- if (rc)
+ vdso_pagelist, vma);
+ if (rc) {
current->mm->context.vdso_base = 0;
-out_up:
+ goto out_err;
+ }
+
+ up_write(&mm->mmap_sem);
+ return 0;
+out_err:
up_write(&mm->mmap_sem);
+ kmem_cache_free(vm_area_cachep, vma);
return rc;
}

diff --git a/arch/sh/kernel/vsyscall/vsyscall.c b/arch/sh/kernel/vsyscall/vsyscall.c
index 5ca5797..f2431da 100644
--- a/arch/sh/kernel/vsyscall/vsyscall.c
+++ b/arch/sh/kernel/vsyscall/vsyscall.c
@@ -10,6 +10,7 @@
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
+#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/init.h>
@@ -61,9 +62,14 @@ int __init vsyscall_init(void)
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
unsigned long addr;
int ret;

+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return -ENOMEM;
+
down_write(&mm->mmap_sem);
addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
if (IS_ERR_VALUE(addr)) {
@@ -74,14 +80,17 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
ret = install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ | VM_EXEC |
VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
- syscall_pages);
+ syscall_pages, vma);
if (unlikely(ret))
goto up_fail;

current->mm->context.vdso = (void *)addr;

+ up_write(&mm->mmap_sem);
+ return 0;
up_fail:
up_write(&mm->mmap_sem);
+ kmem_cache_free(vm_area_cachep, vma);
return ret;
}

diff --git a/arch/tile/kernel/vdso.c b/arch/tile/kernel/vdso.c
index 1533af2..e691c0b 100644
--- a/arch/tile/kernel/vdso.c
+++ b/arch/tile/kernel/vdso.c
@@ -15,6 +15,7 @@
#include <linux/binfmts.h>
#include <linux/compat.h>
#include <linux/elf.h>
+#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/pagemap.h>

@@ -140,6 +141,7 @@ int setup_vdso_pages(void)
{
struct page **pagelist;
unsigned long pages;
+ struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
unsigned long vdso_base = 0;
int retval = 0;
@@ -147,6 +149,10 @@ int setup_vdso_pages(void)
if (!vdso_ready)
return 0;

+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return -ENOMEM;
+
mm->context.vdso_base = 0;

pagelist = vdso_pagelist;
@@ -198,10 +204,11 @@ int setup_vdso_pages(void)
pages << PAGE_SHIFT,
VM_READ|VM_EXEC |
VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
- pagelist);
- if (retval)
+ pagelist, vma);
+ if (retval) {
mm->context.vdso_base = 0;
-
+ kmem_cache_free(vm_area_cachep, vma);
+ }
return retval;
}

diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 007d550..f08cd6c 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -104,18 +104,23 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
void uml_setup_stubs(struct mm_struct *mm)
{
int err, ret;
+ struct vm_area_struct *vma;

if (!skas_needs_stub)
return;

+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return;
+
ret = init_stub_pte(mm, STUB_CODE,
(unsigned long) &__syscall_stub_start);
if (ret)
- goto out;
+ goto err;

ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
if (ret)
- goto out;
+ goto err;

mm->context.stub_pages[0] = virt_to_page(&__syscall_stub_start);
mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack);
@@ -124,14 +129,15 @@ void uml_setup_stubs(struct mm_struct *mm)
err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
VM_READ | VM_MAYREAD | VM_EXEC |
VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP,
- mm->context.stub_pages);
+ mm->context.stub_pages, vma);
if (err) {
printk(KERN_ERR "install_special_mapping returned %d\n", err);
- goto out;
+ goto err;
}
return;

-out:
+err:
+ kmem_cache_free(vm_area_cachep, vma);
force_sigsegv(SIGSEGV, current);
}

diff --git a/arch/unicore32/kernel/process.c b/arch/unicore32/kernel/process.c
index 778ebba..d23adef 100644
--- a/arch/unicore32/kernel/process.c
+++ b/arch/unicore32/kernel/process.c
@@ -14,6 +14,7 @@
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
+#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
@@ -313,12 +314,18 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)

int vectors_user_mapping(void)
{
+ int ret = 0;
+ struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
- return install_special_mapping(mm, 0xffff0000, PAGE_SIZE,
- VM_READ | VM_EXEC |
- VM_MAYREAD | VM_MAYEXEC |
- VM_DONTEXPAND | VM_DONTDUMP,
- NULL);
+
+ ret = install_special_mapping(mm, 0xffff0000, PAGE_SIZE,
+ VM_READ | VM_EXEC |
+ VM_MAYREAD | VM_MAYEXEC |
+ VM_DONTEXPAND | VM_DONTDUMP,
+ NULL, vma);
+ if (ret)
+ kmem_cache_free(vm_area_cachep, vma);
+ return ret;
}

const char *arch_vma_name(struct vm_area_struct *vma)
diff --git a/arch/x86/um/vdso/vma.c b/arch/x86/um/vdso/vma.c
index af91901..a380b13 100644
--- a/arch/x86/um/vdso/vma.c
+++ b/arch/x86/um/vdso/vma.c
@@ -55,19 +55,29 @@ subsys_initcall(init_vdso);
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
int err;
+ struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;

if (!vdso_enabled)
return 0;

+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return -ENOMEM;
+
down_write(&mm->mmap_sem);

err = install_special_mapping(mm, um_vdso_addr, PAGE_SIZE,
- VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- vdsop);
+ VM_READ|VM_EXEC|
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+ vdsop, vma);
+ if (err)
+ goto out_err;

up_write(&mm->mmap_sem);
-
+ return err;
+out_err:
+ up_write(&mm->mmap_sem);
+ kmem_cache_free(vm_area_cachep, vma);
return err;
}
diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
index d6bfb87..efa791a 100644
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -13,6 +13,7 @@
#include <linux/gfp.h>
#include <linux/string.h>
#include <linux/elf.h>
+#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/module.h>
@@ -307,6 +308,7 @@ int __init sysenter_setup(void)
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
unsigned long addr;
int ret = 0;
bool compat;
@@ -319,6 +321,12 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
if (vdso_enabled == VDSO_DISABLED)
return 0;

+ if (compat_uses_vma || !compat) {
+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return -ENOMEM;
+ }
+
down_write(&mm->mmap_sem);

/* Test compat mode once here, in case someone
@@ -346,7 +354,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
ret = install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- vdso32_pages);
+ vdso32_pages, vma);

if (ret)
goto up_fail;
@@ -355,12 +363,18 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
current_thread_info()->sysenter_return =
VDSO32_SYMBOL(addr, SYSENTER_RETURN);

+ up_write(&mm->mmap_sem);
+
+ return ret;
+
up_fail:
if (ret)
current->mm->context.vdso = NULL;

up_write(&mm->mmap_sem);

+ if (ret && (compat_uses_vma || !compat))
+ kmem_cache_free(vm_area_cachep, vma);
return ret;
}

diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index 431e875..fc189de 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -154,12 +154,17 @@ static int setup_additional_pages(struct linux_binprm *bprm,
unsigned size)
{
struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
unsigned long addr;
int ret;

if (!vdso_enabled)
return 0;

+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return -ENOMEM;
+
down_write(&mm->mmap_sem);
addr = vdso_addr(mm->start_stack, size);
addr = get_unmapped_area(NULL, addr, size, 0, 0);
@@ -173,14 +178,17 @@ static int setup_additional_pages(struct linux_binprm *bprm,
ret = install_special_mapping(mm, addr, size,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- pages);
+ pages, vma);
if (ret) {
current->mm->context.vdso = NULL;
goto up_fail;
}

+ up_write(&mm->mmap_sem);
+ return ret;
up_fail:
up_write(&mm->mmap_sem);
+ kmem_cache_free(vm_area_cachep, vma);
return ret;
}

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8b6e55e..ade2bd1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1515,7 +1515,8 @@ extern struct file *get_mm_exe_file(struct mm_struct *mm);
extern int may_expand_vm(struct mm_struct *mm, unsigned long npages);
extern int install_special_mapping(struct mm_struct *mm,
unsigned long addr, unsigned long len,
- unsigned long flags, struct page **pages);
+ unsigned long flags, struct page **pages,
+ struct vm_area_struct *vma);

extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index ad8e1bd..3a99f4b 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1099,8 +1099,14 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
static int xol_add_vma(struct xol_area *area)
{
struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+
int ret = -EALREADY;

+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(!vma))
+ return -ENOMEM;
+
down_write(&mm->mmap_sem);
if (mm->uprobes_state.xol_area)
goto fail;
@@ -1114,16 +1120,20 @@ static int xol_add_vma(struct xol_area *area)
}

ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE,
- VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page);
+ VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO,
+ &area->page, vma);
if (ret)
goto fail;

smp_wmb(); /* pairs with get_xol_area() */
mm->uprobes_state.xol_area = area;
ret = 0;
+
+ up_write(&mm->mmap_sem);
+ return 0;
fail:
up_write(&mm->mmap_sem);
-
+ kmem_cache_free(vm_area_cachep, vma);
return ret;
}

diff --git a/mm/mmap.c b/mm/mmap.c
index 6a7824d..6a6ef0a 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2909,17 +2909,16 @@ static const struct vm_operations_struct special_mapping_vmops = {
* The region past the last page supplied will always produce SIGBUS.
* The array pointer and the pages it points to are assumed to stay alive
* for as long as this mapping might exist.
+ *
+ * The caller has the responsibility of allocating the new vma, and freeing
+ * it if it was unused (when insert_vm_struct() fails).
*/
int install_special_mapping(struct mm_struct *mm,
unsigned long addr, unsigned long len,
- unsigned long vm_flags, struct page **pages)
+ unsigned long vm_flags, struct page **pages,
+ struct vm_area_struct *vma)
{
- int ret;
- struct vm_area_struct *vma;
-
- vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
- if (unlikely(vma == NULL))
- return -ENOMEM;
+ int ret = 0;

INIT_LIST_HEAD(&vma->anon_vma_chain);
vma->vm_mm = mm;
@@ -2939,11 +2938,7 @@ int install_special_mapping(struct mm_struct *mm,
mm->total_vm += len >> PAGE_SHIFT;

perf_event_mmap(vma);
-
- return 0;
-
out:
- kmem_cache_free(vm_area_cachep, vma);
return ret;
}

--
1.8.1.4




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