The patch titled
Subject: treewide: use initializer for struct vm_unmapped_area_info
has been added to the -mm mm-unstable branch. Its filename is
treewide-use-initializer-for-struct-vm_unmapped_area_info.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/treewide-use-initializer-for-struct-vm_unmapped_area_info.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Subject: treewide: use initializer for struct vm_unmapped_area_info
Date: Mon, 25 Mar 2024 19:16:52 -0700
Future changes will need to add a new member to struct
vm_unmapped_area_info. This would cause trouble for any call site that
doesn't initialize the struct. Currently every caller sets each member
manually, so if new ones are added they will be uninitialized and the core
code parsing the struct will see garbage in the new member.
It could be possible to initialize the new member manually to 0 at each
call site. This and a couple other options were discussed. Having some
struct vm_unmapped_area_info instances not zero initialized will put those
sites at risk of feeding garbage into vm_unmapped_area(), if the
convention is to zero initialize the struct and any new field addition
missed a call site that initializes each field manually. So it is useful
to do things similar across the kernel.
The consensus (see links) was that in general the best way to accomplish
taking into account both code cleanliness and minimizing the chance of
introducing bugs, was to do C99 static initialization. As in: struct
vm_unmapped_area_info info = {};
With this method of initialization, the whole struct will be zero
initialized, and any statements setting fields to zero will be unneeded.
The change should not leave cleanup at the call sides.
While iterating though the possible solutions a few archs kindly acked
other variations that still zero initialized the struct. These sites have
been modified in previous changes using the pattern acked by the
respective arch.
So to be reduce the chance of bugs via uninitialized fields, perform a
tree wide change using the consensus for the best general way to do this
change. Use C99 static initializing to zero the struct and remove and
statements that simply set members to zero.
Link: https://lkml.kernel.org/r/20240326021656.202649-11-rick.p.edgecombe@xxxxxxxxx
Link: https://lore.kernel.org/lkml/202402280912.33AEE7A9CF@keescook/#t
Link: https://lore.kernel.org/lkml/j7bfvig3gew3qruouxrh7z7ehjjafrgkbcmg6tcghhfh3rhmzi@wzlcoecgy5rs/
Link: https://lore.kernel.org/lkml/ec3e377a-c0a0-4dd3-9cb9-96517e54d17e@xxxxxxxxxx/
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxx>
Cc: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Deepak Gupta <debug@xxxxxxxxxxxx>
Cc: Guo Ren <guoren@xxxxxxxxxx>
Cc: Helge Deller <deller@xxxxxx>
Cc: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "James E.J. Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/alpha/kernel/osf_sys.c | 5 +----
arch/arc/mm/mmap.c | 4 +---
arch/arm/mm/mmap.c | 5 ++---
arch/loongarch/mm/mmap.c | 3 +--
arch/mips/mm/mmap.c | 3 +--
arch/s390/mm/hugetlbpage.c | 7 ++-----
arch/s390/mm/mmap.c | 5 ++---
arch/sh/mm/mmap.c | 5 ++---
arch/sparc/kernel/sys_sparc_32.c | 3 +--
arch/sparc/kernel/sys_sparc_64.c | 5 ++---
arch/sparc/mm/hugetlbpage.c | 7 ++-----
arch/x86/kernel/sys_x86_64.c | 7 ++-----
arch/x86/mm/hugetlbpage.c | 7 ++-----
fs/hugetlbfs/inode.c | 7 ++-----
mm/mmap.c | 9 ++-------
15 files changed, 25 insertions(+), 57 deletions(-)
--- a/arch/alpha/kernel/osf_sys.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/arch/alpha/kernel/osf_sys.c
@@ -1218,14 +1218,11 @@ static unsigned long
arch_get_unmapped_area_1(unsigned long addr, unsigned long len,
unsigned long limit)
{
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
- info.flags = 0;
info.length = len;
info.low_limit = addr;
info.high_limit = limit;
- info.align_mask = 0;
- info.align_offset = 0;
return vm_unmapped_area(&info);
}
--- a/arch/arc/mm/mmap.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/arch/arc/mm/mmap.c
@@ -27,7 +27,7 @@ arch_get_unmapped_area(struct file *filp
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
/*
* We enforce the MAP_FIXED case.
@@ -51,11 +51,9 @@ arch_get_unmapped_area(struct file *filp
return addr;
}
- info.flags = 0;
info.length = len;
info.low_limit = mm->mmap_base;
info.high_limit = TASK_SIZE;
- info.align_mask = 0;
info.align_offset = pgoff << PAGE_SHIFT;
return vm_unmapped_area(&info);
}
--- a/arch/arm/mm/mmap.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/arch/arm/mm/mmap.c
@@ -34,7 +34,7 @@ arch_get_unmapped_area(struct file *filp
struct vm_area_struct *vma;
int do_align = 0;
int aliasing = cache_is_vipt_aliasing();
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
/*
* We only need to do colour alignment if either the I or D
@@ -68,7 +68,6 @@ arch_get_unmapped_area(struct file *filp
return addr;
}
- info.flags = 0;
info.length = len;
info.low_limit = mm->mmap_base;
info.high_limit = TASK_SIZE;
@@ -87,7 +86,7 @@ arch_get_unmapped_area_topdown(struct fi
unsigned long addr = addr0;
int do_align = 0;
int aliasing = cache_is_vipt_aliasing();
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
/*
* We only need to do colour alignment if either the I or D
--- a/arch/loongarch/mm/mmap.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/arch/loongarch/mm/mmap.c
@@ -24,7 +24,7 @@ static unsigned long arch_get_unmapped_a
struct vm_area_struct *vma;
unsigned long addr = addr0;
int do_color_align;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
if (unlikely(len > TASK_SIZE))
return -ENOMEM;
@@ -82,7 +82,6 @@ static unsigned long arch_get_unmapped_a
*/
}
- info.flags = 0;
info.low_limit = mm->mmap_base;
info.high_limit = TASK_SIZE;
return vm_unmapped_area(&info);
--- a/arch/mips/mm/mmap.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/arch/mips/mm/mmap.c
@@ -34,7 +34,7 @@ static unsigned long arch_get_unmapped_a
struct vm_area_struct *vma;
unsigned long addr = addr0;
int do_color_align;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
if (unlikely(len > TASK_SIZE))
return -ENOMEM;
@@ -92,7 +92,6 @@ static unsigned long arch_get_unmapped_a
*/
}
- info.flags = 0;
info.low_limit = mm->mmap_base;
info.high_limit = TASK_SIZE;
return vm_unmapped_area(&info);
--- a/arch/s390/mm/hugetlbpage.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/arch/s390/mm/hugetlbpage.c
@@ -248,14 +248,12 @@ static unsigned long hugetlb_get_unmappe
unsigned long pgoff, unsigned long flags)
{
struct hstate *h = hstate_file(file);
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
- info.flags = 0;
info.length = len;
info.low_limit = current->mm->mmap_base;
info.high_limit = TASK_SIZE;
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
- info.align_offset = 0;
return vm_unmapped_area(&info);
}
@@ -264,7 +262,7 @@ static unsigned long hugetlb_get_unmappe
unsigned long pgoff, unsigned long flags)
{
struct hstate *h = hstate_file(file);
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
unsigned long addr;
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
@@ -272,7 +270,6 @@ static unsigned long hugetlb_get_unmappe
info.low_limit = PAGE_SIZE;
info.high_limit = current->mm->mmap_base;
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
- info.align_offset = 0;
addr = vm_unmapped_area(&info);
/*
--- a/arch/s390/mm/mmap.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/arch/s390/mm/mmap.c
@@ -86,7 +86,7 @@ unsigned long arch_get_unmapped_area(str
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
if (len > TASK_SIZE - mmap_min_addr)
return -ENOMEM;
@@ -102,7 +102,6 @@ unsigned long arch_get_unmapped_area(str
goto check_asce_limit;
}
- info.flags = 0;
info.length = len;
info.low_limit = mm->mmap_base;
info.high_limit = TASK_SIZE;
@@ -122,7 +121,7 @@ unsigned long arch_get_unmapped_area_top
{
struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
/* requested length too big for entire address space */
if (len > TASK_SIZE - mmap_min_addr)
--- a/arch/sh/mm/mmap.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/arch/sh/mm/mmap.c
@@ -57,7 +57,7 @@ unsigned long arch_get_unmapped_area(str
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
int do_colour_align;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
if (flags & MAP_FIXED) {
/* We do not accept a shared mapping if it would violate
@@ -88,7 +88,6 @@ unsigned long arch_get_unmapped_area(str
return addr;
}
- info.flags = 0;
info.length = len;
info.low_limit = TASK_UNMAPPED_BASE;
info.high_limit = TASK_SIZE;
@@ -106,7 +105,7 @@ arch_get_unmapped_area_topdown(struct fi
struct mm_struct *mm = current->mm;
unsigned long addr = addr0;
int do_colour_align;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
if (flags & MAP_FIXED) {
/* We do not accept a shared mapping if it would violate
--- a/arch/sparc/kernel/sys_sparc_32.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/arch/sparc/kernel/sys_sparc_32.c
@@ -41,7 +41,7 @@ SYSCALL_DEFINE0(getpagesize)
unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags)
{
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
if (flags & MAP_FIXED) {
/* We do not accept a shared mapping if it would violate
@@ -59,7 +59,6 @@ unsigned long arch_get_unmapped_area(str
if (!addr)
addr = TASK_UNMAPPED_BASE;
- info.flags = 0;
info.length = len;
info.low_limit = addr;
info.high_limit = TASK_SIZE;
--- a/arch/sparc/kernel/sys_sparc_64.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/arch/sparc/kernel/sys_sparc_64.c
@@ -93,7 +93,7 @@ unsigned long arch_get_unmapped_area(str
struct vm_area_struct * vma;
unsigned long task_size = TASK_SIZE;
int do_color_align;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
if (flags & MAP_FIXED) {
/* We do not accept a shared mapping if it would violate
@@ -126,7 +126,6 @@ unsigned long arch_get_unmapped_area(str
return addr;
}
- info.flags = 0;
info.length = len;
info.low_limit = TASK_UNMAPPED_BASE;
info.high_limit = min(task_size, VA_EXCLUDE_START);
@@ -154,7 +153,7 @@ arch_get_unmapped_area_topdown(struct fi
unsigned long task_size = STACK_TOP32;
unsigned long addr = addr0;
int do_color_align;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
/* This should only ever run for 32-bit processes. */
BUG_ON(!test_thread_flag(TIF_32BIT));
--- a/arch/sparc/mm/hugetlbpage.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/arch/sparc/mm/hugetlbpage.c
@@ -31,17 +31,15 @@ static unsigned long hugetlb_get_unmappe
{
struct hstate *h = hstate_file(filp);
unsigned long task_size = TASK_SIZE;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
if (test_thread_flag(TIF_32BIT))
task_size = STACK_TOP32;
- info.flags = 0;
info.length = len;
info.low_limit = TASK_UNMAPPED_BASE;
info.high_limit = min(task_size, VA_EXCLUDE_START);
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
- info.align_offset = 0;
addr = vm_unmapped_area(&info);
if ((addr & ~PAGE_MASK) && task_size > VA_EXCLUDE_END) {
@@ -63,7 +61,7 @@ hugetlb_get_unmapped_area_topdown(struct
struct hstate *h = hstate_file(filp);
struct mm_struct *mm = current->mm;
unsigned long addr = addr0;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
/* This should only ever run for 32-bit processes. */
BUG_ON(!test_thread_flag(TIF_32BIT));
@@ -73,7 +71,6 @@ hugetlb_get_unmapped_area_topdown(struct
info.low_limit = PAGE_SIZE;
info.high_limit = mm->mmap_base;
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
- info.align_offset = 0;
addr = vm_unmapped_area(&info);
/*
--- a/arch/x86/kernel/sys_x86_64.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/arch/x86/kernel/sys_x86_64.c
@@ -118,7 +118,7 @@ arch_get_unmapped_area(struct file *filp
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
unsigned long begin, end;
if (flags & MAP_FIXED)
@@ -137,11 +137,9 @@ arch_get_unmapped_area(struct file *filp
return addr;
}
- info.flags = 0;
info.length = len;
info.low_limit = begin;
info.high_limit = end;
- info.align_mask = 0;
info.align_offset = pgoff << PAGE_SHIFT;
if (filp) {
info.align_mask = get_align_mask();
@@ -158,7 +156,7 @@ arch_get_unmapped_area_topdown(struct fi
struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
unsigned long addr = addr0;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
/* requested length too big for entire address space */
if (len > TASK_SIZE)
@@ -203,7 +201,6 @@ get_unmapped_area:
if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall())
info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
- info.align_mask = 0;
info.align_offset = pgoff << PAGE_SHIFT;
if (filp) {
info.align_mask = get_align_mask();
--- a/arch/x86/mm/hugetlbpage.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/arch/x86/mm/hugetlbpage.c
@@ -25,9 +25,8 @@ static unsigned long hugetlb_get_unmappe
unsigned long pgoff, unsigned long flags)
{
struct hstate *h = hstate_file(file);
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
- info.flags = 0;
info.length = len;
info.low_limit = get_mmap_base(1);
@@ -39,7 +38,6 @@ static unsigned long hugetlb_get_unmappe
task_size_32bit() : task_size_64bit(addr > DEFAULT_MAP_WINDOW);
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
- info.align_offset = 0;
return vm_unmapped_area(&info);
}
@@ -48,7 +46,7 @@ static unsigned long hugetlb_get_unmappe
unsigned long pgoff, unsigned long flags)
{
struct hstate *h = hstate_file(file);
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
info.length = len;
@@ -63,7 +61,6 @@ static unsigned long hugetlb_get_unmappe
info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
- info.align_offset = 0;
addr = vm_unmapped_area(&info);
/*
--- a/fs/hugetlbfs/inode.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/fs/hugetlbfs/inode.c
@@ -176,14 +176,12 @@ hugetlb_get_unmapped_area_bottomup(struc
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct hstate *h = hstate_file(file);
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
- info.flags = 0;
info.length = len;
info.low_limit = current->mm->mmap_base;
info.high_limit = arch_get_mmap_end(addr, len, flags);
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
- info.align_offset = 0;
return vm_unmapped_area(&info);
}
@@ -192,14 +190,13 @@ hugetlb_get_unmapped_area_topdown(struct
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct hstate *h = hstate_file(file);
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
info.length = len;
info.low_limit = PAGE_SIZE;
info.high_limit = arch_get_mmap_base(addr, current->mm->mmap_base);
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
- info.align_offset = 0;
addr = vm_unmapped_area(&info);
/*
--- a/mm/mmap.c~treewide-use-initializer-for-struct-vm_unmapped_area_info
+++ a/mm/mmap.c
@@ -1704,7 +1704,7 @@ generic_get_unmapped_area(struct file *f
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma, *prev;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
if (len > mmap_end - mmap_min_addr)
@@ -1722,12 +1722,9 @@ generic_get_unmapped_area(struct file *f
return addr;
}
- info.flags = 0;
info.length = len;
info.low_limit = mm->mmap_base;
info.high_limit = mmap_end;
- info.align_mask = 0;
- info.align_offset = 0;
return vm_unmapped_area(&info);
}
@@ -1752,7 +1749,7 @@ generic_get_unmapped_area_topdown(struct
{
struct vm_area_struct *vma, *prev;
struct mm_struct *mm = current->mm;
- struct vm_unmapped_area_info info;
+ struct vm_unmapped_area_info info = {};
const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
/* requested length too big for entire address space */
@@ -1776,8 +1773,6 @@ generic_get_unmapped_area_topdown(struct
info.length = len;
info.low_limit = PAGE_SIZE;
info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
- info.align_mask = 0;
- info.align_offset = 0;
addr = vm_unmapped_area(&info);
/*
_
Patches currently in -mm which might be from rick.p.edgecombe@xxxxxxxxx are
proc-refactor-pde_get_unmapped_area-as-prep.patch
mm-switch-mm-get_unmapped_area-to-a-flag.patch
mm-introduce-arch_get_unmapped_area_vmflags.patch
mm-remove-export-for-get_unmapped_area.patch
mm-use-get_unmapped_area_vmflags.patch
thp-add-thp_get_unmapped_area_vmflags.patch
csky-use-initializer-for-struct-vm_unmapped_area_info.patch
parisc-use-initializer-for-struct-vm_unmapped_area_info.patch
powerpc-use-initializer-for-struct-vm_unmapped_area_info.patch
treewide-use-initializer-for-struct-vm_unmapped_area_info.patch
mm-take-placement-mappings-gap-into-account.patch
x86-mm-implement-have_arch_unmapped_area_vmflags.patch
x86-mm-care-about-shadow-stack-guard-gap-during-placement.patch
selftests-x86-add-placement-guard-gap-test-for-shstk.patch
