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-rw-r--r--mm/mmap.c249
1 files changed, 169 insertions, 80 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 455772a05e54..3f8142e22490 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -58,6 +58,18 @@
#define arch_rebalance_pgtables(addr, len) (addr)
#endif
+#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
+const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
+const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
+int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
+#endif
+#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
+const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
+const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
+int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
+#endif
+
+
static void unmap_region(struct mm_struct *mm,
struct vm_area_struct *vma, struct vm_area_struct *prev,
unsigned long start, unsigned long end);
@@ -288,6 +300,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
unsigned long retval;
unsigned long newbrk, oldbrk;
struct mm_struct *mm = current->mm;
+ struct vm_area_struct *next;
unsigned long min_brk;
bool populate;
@@ -332,7 +345,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
}
/* Check against existing mmap mappings. */
- if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
+ next = find_vma(mm, oldbrk);
+ if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
goto out;
/* Ok, looks good - let it rip. */
@@ -355,10 +369,22 @@ out:
static long vma_compute_subtree_gap(struct vm_area_struct *vma)
{
- unsigned long max, subtree_gap;
- max = vma->vm_start;
- if (vma->vm_prev)
- max -= vma->vm_prev->vm_end;
+ unsigned long max, prev_end, subtree_gap;
+
+ /*
+ * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
+ * allow two stack_guard_gaps between them here, and when choosing
+ * an unmapped area; whereas when expanding we only require one.
+ * That's a little inconsistent, but keeps the code here simpler.
+ */
+ max = vm_start_gap(vma);
+ if (vma->vm_prev) {
+ prev_end = vm_end_gap(vma->vm_prev);
+ if (max > prev_end)
+ max -= prev_end;
+ else
+ max = 0;
+ }
if (vma->vm_rb.rb_left) {
subtree_gap = rb_entry(vma->vm_rb.rb_left,
struct vm_area_struct, vm_rb)->rb_subtree_gap;
@@ -451,7 +477,7 @@ static void validate_mm(struct mm_struct *mm)
anon_vma_unlock_read(anon_vma);
}
- highest_address = vma->vm_end;
+ highest_address = vm_end_gap(vma);
vma = vma->vm_next;
i++;
}
@@ -620,7 +646,7 @@ void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
if (vma->vm_next)
vma_gap_update(vma->vm_next);
else
- mm->highest_vm_end = vma->vm_end;
+ mm->highest_vm_end = vm_end_gap(vma);
/*
* vma->vm_prev wasn't known when we followed the rbtree to find the
@@ -866,7 +892,7 @@ again: remove_next = 1 + (end > next->vm_end);
vma_gap_update(vma);
if (end_changed) {
if (!next)
- mm->highest_vm_end = end;
+ mm->highest_vm_end = vm_end_gap(vma);
else if (!adjust_next)
vma_gap_update(next);
}
@@ -909,7 +935,7 @@ again: remove_next = 1 + (end > next->vm_end);
else if (next)
vma_gap_update(next);
else
- mm->highest_vm_end = end;
+ VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
}
if (insert && file)
uprobe_mmap(insert);
@@ -925,7 +951,8 @@ again: remove_next = 1 + (end > next->vm_end);
*/
static inline int is_mergeable_vma(struct vm_area_struct *vma,
struct file *file, unsigned long vm_flags,
- struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
+ const char __user *anon_name)
{
/*
* VM_SOFTDIRTY should not prevent from VMA merging, if we
@@ -943,6 +970,8 @@ static inline int is_mergeable_vma(struct vm_area_struct *vma,
return 0;
if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
return 0;
+ if (vma_get_anon_name(vma) != anon_name)
+ return 0;
return 1;
}
@@ -975,9 +1004,10 @@ static int
can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
struct anon_vma *anon_vma, struct file *file,
pgoff_t vm_pgoff,
- struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
+ const char __user *anon_name)
{
- if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
+ if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name) &&
is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
if (vma->vm_pgoff == vm_pgoff)
return 1;
@@ -996,9 +1026,10 @@ static int
can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
struct anon_vma *anon_vma, struct file *file,
pgoff_t vm_pgoff,
- struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
+ const char __user *anon_name)
{
- if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
+ if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name) &&
is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
pgoff_t vm_pglen;
vm_pglen = vma_pages(vma);
@@ -1009,9 +1040,9 @@ can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
}
/*
- * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
- * whether that can be merged with its predecessor or its successor.
- * Or both (it neatly fills a hole).
+ * Given a mapping request (addr,end,vm_flags,file,pgoff,anon_name),
+ * figure out whether that can be merged with its predecessor or its
+ * successor. Or both (it neatly fills a hole).
*
* In most cases - when called for mmap, brk or mremap - [addr,end) is
* certain not to be mapped by the time vma_merge is called; but when
@@ -1042,7 +1073,8 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
unsigned long end, unsigned long vm_flags,
struct anon_vma *anon_vma, struct file *file,
pgoff_t pgoff, struct mempolicy *policy,
- struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
+ const char __user *anon_name)
{
pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
struct vm_area_struct *area, *next;
@@ -1070,7 +1102,8 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
mpol_equal(vma_policy(prev), policy) &&
can_vma_merge_after(prev, vm_flags,
anon_vma, file, pgoff,
- vm_userfaultfd_ctx)) {
+ vm_userfaultfd_ctx,
+ anon_name)) {
/*
* OK, it can. Can we now merge in the successor as well?
*/
@@ -1079,7 +1112,8 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
can_vma_merge_before(next, vm_flags,
anon_vma, file,
pgoff+pglen,
- vm_userfaultfd_ctx) &&
+ vm_userfaultfd_ctx,
+ anon_name) &&
is_mergeable_anon_vma(prev->anon_vma,
next->anon_vma, NULL)) {
/* cases 1, 6 */
@@ -1101,7 +1135,8 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
mpol_equal(policy, vma_policy(next)) &&
can_vma_merge_before(next, vm_flags,
anon_vma, file, pgoff+pglen,
- vm_userfaultfd_ctx)) {
+ vm_userfaultfd_ctx,
+ anon_name)) {
if (prev && addr < prev->vm_end) /* case 4 */
err = vma_adjust(prev, prev->vm_start,
addr, prev->vm_pgoff, NULL);
@@ -1261,6 +1296,35 @@ static inline int mlock_future_check(struct mm_struct *mm,
return 0;
}
+static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
+{
+ if (S_ISREG(inode->i_mode))
+ return MAX_LFS_FILESIZE;
+
+ if (S_ISBLK(inode->i_mode))
+ return MAX_LFS_FILESIZE;
+
+ /* Special "we do even unsigned file positions" case */
+ if (file->f_mode & FMODE_UNSIGNED_OFFSET)
+ return 0;
+
+ /* Yes, random drivers might want more. But I'm tired of buggy drivers */
+ return ULONG_MAX;
+}
+
+static inline bool file_mmap_ok(struct file *file, struct inode *inode,
+ unsigned long pgoff, unsigned long len)
+{
+ u64 maxsize = file_mmap_size_max(file, inode);
+
+ if (maxsize && len > maxsize)
+ return false;
+ maxsize -= len;
+ if (pgoff > maxsize >> PAGE_SHIFT)
+ return false;
+ return true;
+}
+
/*
* The caller must hold down_write(&current->mm->mmap_sem).
*/
@@ -1326,6 +1390,9 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
if (file) {
struct inode *inode = file_inode(file);
+ if (!file_mmap_ok(file, inode, pgoff, len))
+ return -EOVERFLOW;
+
switch (flags & MAP_TYPE) {
case MAP_SHARED:
if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
@@ -1585,7 +1652,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
* Can we just expand an old mapping?
*/
vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
- NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
+ NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX, NULL);
if (vma)
goto out;
@@ -1741,7 +1808,7 @@ unsigned long unmapped_area(struct vm_unmapped_area_info *info)
while (true) {
/* Visit left subtree if it looks promising */
- gap_end = vma->vm_start;
+ gap_end = vm_start_gap(vma);
if (gap_end >= low_limit && vma->vm_rb.rb_left) {
struct vm_area_struct *left =
rb_entry(vma->vm_rb.rb_left,
@@ -1752,12 +1819,13 @@ unsigned long unmapped_area(struct vm_unmapped_area_info *info)
}
}
- gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
+ gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
check_current:
/* Check if current node has a suitable gap */
if (gap_start > high_limit)
return -ENOMEM;
- if (gap_end >= low_limit && gap_end - gap_start >= length)
+ if (gap_end >= low_limit &&
+ gap_end > gap_start && gap_end - gap_start >= length)
goto found;
/* Visit right subtree if it looks promising */
@@ -1779,8 +1847,8 @@ check_current:
vma = rb_entry(rb_parent(prev),
struct vm_area_struct, vm_rb);
if (prev == vma->vm_rb.rb_left) {
- gap_start = vma->vm_prev->vm_end;
- gap_end = vma->vm_start;
+ gap_start = vm_end_gap(vma->vm_prev);
+ gap_end = vm_start_gap(vma);
goto check_current;
}
}
@@ -1844,7 +1912,7 @@ unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
while (true) {
/* Visit right subtree if it looks promising */
- gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
+ gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
if (gap_start <= high_limit && vma->vm_rb.rb_right) {
struct vm_area_struct *right =
rb_entry(vma->vm_rb.rb_right,
@@ -1857,10 +1925,11 @@ unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
check_current:
/* Check if current node has a suitable gap */
- gap_end = vma->vm_start;
+ gap_end = vm_start_gap(vma);
if (gap_end < low_limit)
return -ENOMEM;
- if (gap_start <= high_limit && gap_end - gap_start >= length)
+ if (gap_start <= high_limit &&
+ gap_end > gap_start && gap_end - gap_start >= length)
goto found;
/* Visit left subtree if it looks promising */
@@ -1883,7 +1952,7 @@ check_current:
struct vm_area_struct, vm_rb);
if (prev == vma->vm_rb.rb_right) {
gap_start = vma->vm_prev ?
- vma->vm_prev->vm_end : 0;
+ vm_end_gap(vma->vm_prev) : 0;
goto check_current;
}
}
@@ -1921,7 +1990,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
- struct vm_area_struct *vma;
+ struct vm_area_struct *vma, *prev;
struct vm_unmapped_area_info info;
if (len > TASK_SIZE - mmap_min_addr)
@@ -1932,9 +2001,10 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
if (addr) {
addr = PAGE_ALIGN(addr);
- vma = find_vma(mm, addr);
+ vma = find_vma_prev(mm, addr, &prev);
if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)) &&
+ (!prev || addr >= vm_end_gap(prev)))
return addr;
}
@@ -1957,7 +2027,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
const unsigned long len, const unsigned long pgoff,
const unsigned long flags)
{
- struct vm_area_struct *vma;
+ struct vm_area_struct *vma, *prev;
struct mm_struct *mm = current->mm;
unsigned long addr = addr0;
struct vm_unmapped_area_info info;
@@ -1972,9 +2042,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
/* requesting a specific address */
if (addr) {
addr = PAGE_ALIGN(addr);
- vma = find_vma(mm, addr);
+ vma = find_vma_prev(mm, addr, &prev);
if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
- (!vma || addr + len <= vma->vm_start))
+ (!vma || addr + len <= vm_start_gap(vma)) &&
+ (!prev || addr >= vm_end_gap(prev)))
return addr;
}
@@ -2099,21 +2170,19 @@ find_vma_prev(struct mm_struct *mm, unsigned long addr,
* update accounting. This is shared with both the
* grow-up and grow-down cases.
*/
-static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
+static int acct_stack_growth(struct vm_area_struct *vma,
+ unsigned long size, unsigned long grow)
{
struct mm_struct *mm = vma->vm_mm;
struct rlimit *rlim = current->signal->rlim;
- unsigned long new_start, actual_size;
+ unsigned long new_start;
/* address space limit tests */
if (!may_expand_vm(mm, grow))
return -ENOMEM;
/* Stack limit test */
- actual_size = size;
- if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
- actual_size -= PAGE_SIZE;
- if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
+ if (size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
return -ENOMEM;
/* mlock limit tests */
@@ -2151,16 +2220,33 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
int expand_upwards(struct vm_area_struct *vma, unsigned long address)
{
struct mm_struct *mm = vma->vm_mm;
+ struct vm_area_struct *next;
+ unsigned long gap_addr;
int error = 0;
if (!(vma->vm_flags & VM_GROWSUP))
return -EFAULT;
- /* Guard against wrapping around to address 0. */
- if (address < PAGE_ALIGN(address+4))
- address = PAGE_ALIGN(address+4);
- else
+ /* Guard against exceeding limits of the address space. */
+ address &= PAGE_MASK;
+ if (address >= (TASK_SIZE & PAGE_MASK))
return -ENOMEM;
+ address += PAGE_SIZE;
+
+ /* Enforce stack_guard_gap */
+ gap_addr = address + stack_guard_gap;
+
+ /* Guard against overflow */
+ if (gap_addr < address || gap_addr > TASK_SIZE)
+ gap_addr = TASK_SIZE;
+
+ next = vma->vm_next;
+ if (next && next->vm_start < gap_addr &&
+ (next->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) {
+ if (!(next->vm_flags & VM_GROWSUP))
+ return -ENOMEM;
+ /* Check that both stack segments have the same anon_vma? */
+ }
/* We must make sure the anon_vma is allocated. */
if (unlikely(anon_vma_prepare(vma)))
@@ -2206,7 +2292,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
if (vma->vm_next)
vma_gap_update(vma->vm_next);
else
- mm->highest_vm_end = address;
+ mm->highest_vm_end = vm_end_gap(vma);
spin_unlock(&mm->page_table_lock);
perf_event_mmap(vma);
@@ -2227,6 +2313,8 @@ int expand_downwards(struct vm_area_struct *vma,
unsigned long address)
{
struct mm_struct *mm = vma->vm_mm;
+ struct vm_area_struct *prev;
+ unsigned long gap_addr;
int error;
address &= PAGE_MASK;
@@ -2234,6 +2322,18 @@ int expand_downwards(struct vm_area_struct *vma,
if (error)
return error;
+ /* Enforce stack_guard_gap */
+ gap_addr = address - stack_guard_gap;
+ if (gap_addr > address)
+ return -ENOMEM;
+ prev = vma->vm_prev;
+ if (prev && prev->vm_end > gap_addr &&
+ (prev->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) {
+ if (!(prev->vm_flags & VM_GROWSDOWN))
+ return -ENOMEM;
+ /* Check that both stack segments have the same anon_vma? */
+ }
+
/* We must make sure the anon_vma is allocated. */
if (unlikely(anon_vma_prepare(vma)))
return -ENOMEM;
@@ -2289,28 +2389,25 @@ int expand_downwards(struct vm_area_struct *vma,
return error;
}
-/*
- * Note how expand_stack() refuses to expand the stack all the way to
- * abut the next virtual mapping, *unless* that mapping itself is also
- * a stack mapping. We want to leave room for a guard page, after all
- * (the guard page itself is not added here, that is done by the
- * actual page faulting logic)
- *
- * This matches the behavior of the guard page logic (see mm/memory.c:
- * check_stack_guard_page()), which only allows the guard page to be
- * removed under these circumstances.
- */
+/* enforced gap between the expanding stack and other mappings. */
+unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
+
+static int __init cmdline_parse_stack_guard_gap(char *p)
+{
+ unsigned long val;
+ char *endptr;
+
+ val = simple_strtoul(p, &endptr, 10);
+ if (!*endptr)
+ stack_guard_gap = val << PAGE_SHIFT;
+
+ return 0;
+}
+__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
+
#ifdef CONFIG_STACK_GROWSUP
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
- struct vm_area_struct *next;
-
- address &= PAGE_MASK;
- next = vma->vm_next;
- if (next && next->vm_start == address + PAGE_SIZE) {
- if (!(next->vm_flags & VM_GROWSUP))
- return -ENOMEM;
- }
return expand_upwards(vma, address);
}
@@ -2332,14 +2429,6 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr)
#else
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
- struct vm_area_struct *prev;
-
- address &= PAGE_MASK;
- prev = vma->vm_prev;
- if (prev && prev->vm_end == address) {
- if (!(prev->vm_flags & VM_GROWSDOWN))
- return -ENOMEM;
- }
return expand_downwards(vma, address);
}
@@ -2437,7 +2526,7 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
vma->vm_prev = prev;
vma_gap_update(vma);
} else
- mm->highest_vm_end = prev ? prev->vm_end : 0;
+ mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
tail_vma->vm_next = NULL;
/* Kill the cache */
@@ -2613,6 +2702,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
return 0;
}
+EXPORT_SYMBOL(do_munmap);
int vm_munmap(unsigned long start, size_t len)
{
@@ -2646,8 +2736,7 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
unsigned long ret = -EINVAL;
struct file *file;
- pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. "
- "See Documentation/vm/remap_file_pages.txt.\n",
+ pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.txt.\n",
current->comm, current->pid);
if (prot)
@@ -2790,7 +2879,7 @@ static unsigned long do_brk(unsigned long addr, unsigned long len)
/* Can we just expand an old private anonymous mapping? */
vma = vma_merge(mm, prev, addr, addr + len, flags,
- NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
+ NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX, NULL);
if (vma)
goto out;
@@ -2948,7 +3037,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
return NULL; /* should never get here */
new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
- vma->vm_userfaultfd_ctx);
+ vma->vm_userfaultfd_ctx, vma_get_anon_name(vma));
if (new_vma) {
/*
* Source vma may have been merged into new_vma
generated by cgit v1.2.3 (git 2.25.1) at 2025-12-08 16:16:30 +0000