diff options
Diffstat (limited to 'meta-rcar-gen2/recipes-kernel/linux/linux-renesas/0001-SEC-Backport-mm-larger-stack-guard-gap-between-vmas.patch')
| -rw-r--r-- | meta-rcar-gen2/recipes-kernel/linux/linux-renesas/0001-SEC-Backport-mm-larger-stack-guard-gap-between-vmas.patch | 797 |
1 files changed, 797 insertions, 0 deletions
diff --git a/meta-rcar-gen2/recipes-kernel/linux/linux-renesas/0001-SEC-Backport-mm-larger-stack-guard-gap-between-vmas.patch b/meta-rcar-gen2/recipes-kernel/linux/linux-renesas/0001-SEC-Backport-mm-larger-stack-guard-gap-between-vmas.patch new file mode 100644 index 0000000..002e9f1 --- /dev/null +++ b/meta-rcar-gen2/recipes-kernel/linux/linux-renesas/0001-SEC-Backport-mm-larger-stack-guard-gap-between-vmas.patch @@ -0,0 +1,797 @@ +From 0558b5c626426017848d9f3b7af380494c3deece Mon Sep 17 00:00:00 2001 +From: =?UTF-8?q?Jan-Simon=20M=C3=B6ller?= <jsmoeller@linuxfoundation.org> +Date: Tue, 27 Jun 2017 22:46:11 +0200 +Subject: [PATCH 1/3] [SEC][Backport] mm: larger stack guard gap, between vmas +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +This change backports +https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/patch/?id=1ad9a25dd06fda9bdc27875e1cedb8277accb212 + +Signed-off-by: Jan-Simon Möller <jsmoeller@linuxfoundation.org> +--- + Documentation/kernel-parameters.txt | 7 ++ + arch/arc/mm/mmap.c | 2 +- + arch/arm/mm/mmap.c | 4 +- + arch/frv/mm/elf-fdpic.c | 2 +- + arch/mips/mm/mmap.c | 2 +- + arch/powerpc/mm/slice.c | 2 +- + arch/sh/mm/mmap.c | 4 +- + arch/sparc/kernel/sys_sparc_64.c | 4 +- + arch/sparc/mm/hugetlbpage.c | 2 +- + arch/tile/mm/hugetlbpage.c | 2 +- + arch/x86/kernel/sys_x86_64.c | 4 +- + arch/x86/mm/hugetlbpage.c | 2 +- + arch/xtensa/kernel/syscall.c | 2 +- + fs/hugetlbfs/inode.c | 2 +- + fs/proc/task_mmu.c | 4 - + include/linux/mm.h | 53 ++++++------ + mm/memory.c | 49 ----------- + mm/mmap.c | 168 ++++++++++++++++++++---------------- + 18 files changed, 144 insertions(+), 171 deletions(-) + +diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt +index 9859ddf..09924a9 100644 +--- a/Documentation/kernel-parameters.txt ++++ b/Documentation/kernel-parameters.txt +@@ -2884,6 +2884,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. + spia_pedr= + spia_peddr= + ++ stack_guard_gap= [MM] ++ override the default stack gap protection. The value ++ is in page units and it defines how many pages prior ++ to (for stacks growing down) resp. after (for stacks ++ growing up) the main stack are reserved for no other ++ mapping. Default value is 256 pages. ++ + stacktrace [FTRACE] + Enabled the stack tracer on boot up. + +diff --git a/arch/arc/mm/mmap.c b/arch/arc/mm/mmap.c +index 2e06d56..cf4ae69 100644 +--- a/arch/arc/mm/mmap.c ++++ b/arch/arc/mm/mmap.c +@@ -64,7 +64,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr, + + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + +diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c +index 5ef506c..984509e 100644 +--- a/arch/arm/mm/mmap.c ++++ b/arch/arm/mm/mmap.c +@@ -89,7 +89,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr, + + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + +@@ -140,7 +140,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, + addr = PAGE_ALIGN(addr); + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + +diff --git a/arch/frv/mm/elf-fdpic.c b/arch/frv/mm/elf-fdpic.c +index 836f147..efa59f1 100644 +--- a/arch/frv/mm/elf-fdpic.c ++++ b/arch/frv/mm/elf-fdpic.c +@@ -74,7 +74,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi + addr = PAGE_ALIGN(addr); + vma = find_vma(current->mm, addr); + if (TASK_SIZE - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + goto success; + } + +diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c +index 7e5fe27..0bb4295 100644 +--- a/arch/mips/mm/mmap.c ++++ b/arch/mips/mm/mmap.c +@@ -92,7 +92,7 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp, + + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + +diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c +index 7ce9cf3..887365a 100644 +--- a/arch/powerpc/mm/slice.c ++++ b/arch/powerpc/mm/slice.c +@@ -103,7 +103,7 @@ static int slice_area_is_free(struct mm_struct *mm, unsigned long addr, + if ((mm->task_size - len) < addr) + return 0; + vma = find_vma(mm, addr); +- return (!vma || (addr + len) <= vma->vm_start); ++ return (!vma || (addr + len) <= vm_start_gap(vma)); + } + + static int slice_low_has_vma(struct mm_struct *mm, unsigned long slice) +diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c +index 6777177..7df7d59 100644 +--- a/arch/sh/mm/mmap.c ++++ b/arch/sh/mm/mmap.c +@@ -63,7 +63,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, + + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + +@@ -113,7 +113,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, + + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + +diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c +index 2daaaa6..79b981e 100644 +--- a/arch/sparc/kernel/sys_sparc_64.c ++++ b/arch/sparc/kernel/sys_sparc_64.c +@@ -119,7 +119,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi + + vma = find_vma(mm, addr); + if (task_size - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + +@@ -182,7 +182,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, + + vma = find_vma(mm, addr); + if (task_size - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + +diff --git a/arch/sparc/mm/hugetlbpage.c b/arch/sparc/mm/hugetlbpage.c +index d2b5944..ce49370 100644 +--- a/arch/sparc/mm/hugetlbpage.c ++++ b/arch/sparc/mm/hugetlbpage.c +@@ -118,7 +118,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr, + addr = ALIGN(addr, HPAGE_SIZE); + vma = find_vma(mm, addr); + if (task_size - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + if (mm->get_unmapped_area == arch_get_unmapped_area) +diff --git a/arch/tile/mm/hugetlbpage.c b/arch/tile/mm/hugetlbpage.c +index 650ccff..c75eac7 100644 +--- a/arch/tile/mm/hugetlbpage.c ++++ b/arch/tile/mm/hugetlbpage.c +@@ -297,7 +297,7 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, + addr = ALIGN(addr, huge_page_size(h)); + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + if (current->mm->get_unmapped_area == arch_get_unmapped_area) +diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c +index 30277e2..d050393 100644 +--- a/arch/x86/kernel/sys_x86_64.c ++++ b/arch/x86/kernel/sys_x86_64.c +@@ -127,7 +127,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr, + addr = PAGE_ALIGN(addr); + vma = find_vma(mm, addr); + if (end - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + +@@ -166,7 +166,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, + addr = PAGE_ALIGN(addr); + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + +diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c +index ae1aa71..6adf3d9 100644 +--- a/arch/x86/mm/hugetlbpage.c ++++ b/arch/x86/mm/hugetlbpage.c +@@ -341,7 +341,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr, + addr = ALIGN(addr, huge_page_size(h)); + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + if (mm->get_unmapped_area == arch_get_unmapped_area) +diff --git a/arch/xtensa/kernel/syscall.c b/arch/xtensa/kernel/syscall.c +index 5d3f7a1..1ff0b92 100644 +--- a/arch/xtensa/kernel/syscall.c ++++ b/arch/xtensa/kernel/syscall.c +@@ -86,7 +86,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, + /* At this point: (!vmm || addr < vmm->vm_end). */ + if (TASK_SIZE - len < addr) + return -ENOMEM; +- if (!vmm || addr + len <= vmm->vm_start) ++ if (!vmm || addr + len <= vm_start_gap(vmm)) + return addr; + addr = vmm->vm_end; + if (flags & MAP_SHARED) +diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c +index 4e5f332..db7d89c 100644 +--- a/fs/hugetlbfs/inode.c ++++ b/fs/hugetlbfs/inode.c +@@ -169,7 +169,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr, + addr = ALIGN(addr, huge_page_size(h)); + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && +- (!vma || addr + len <= vma->vm_start)) ++ (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + +diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c +index 65fc60a..a5884ed 100644 +--- a/fs/proc/task_mmu.c ++++ b/fs/proc/task_mmu.c +@@ -279,11 +279,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid) + + /* We don't show the stack guard page in /proc/maps */ + start = vma->vm_start; +- if (stack_guard_page_start(vma, start)) +- start += PAGE_SIZE; + end = vma->vm_end; +- if (stack_guard_page_end(vma, end)) +- end -= PAGE_SIZE; + + seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n", + start, +diff --git a/include/linux/mm.h b/include/linux/mm.h +index 263b405..294a6b1 100644 +--- a/include/linux/mm.h ++++ b/include/linux/mm.h +@@ -1056,34 +1056,6 @@ int set_page_dirty(struct page *page); + int set_page_dirty_lock(struct page *page); + int clear_page_dirty_for_io(struct page *page); + +-/* Is the vma a continuation of the stack vma above it? */ +-static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr) +-{ +- return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN); +-} +- +-static inline int stack_guard_page_start(struct vm_area_struct *vma, +- unsigned long addr) +-{ +- return (vma->vm_flags & VM_GROWSDOWN) && +- (vma->vm_start == addr) && +- !vma_growsdown(vma->vm_prev, addr); +-} +- +-/* Is the vma a continuation of the stack vma below it? */ +-static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr) +-{ +- return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP); +-} +- +-static inline int stack_guard_page_end(struct vm_area_struct *vma, +- unsigned long addr) +-{ +- return (vma->vm_flags & VM_GROWSUP) && +- (vma->vm_end == addr) && +- !vma_growsup(vma->vm_next, addr); +-} +- + extern pid_t + vm_is_stack(struct task_struct *task, struct vm_area_struct *vma, int in_group); + +@@ -1609,6 +1581,7 @@ unsigned long ra_submit(struct file_ra_state *ra, + struct address_space *mapping, + struct file *filp); + ++extern unsigned long stack_guard_gap; + /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */ + extern int expand_stack(struct vm_area_struct *vma, unsigned long address); + +@@ -1637,6 +1610,30 @@ static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * m + return vma; + } + ++static inline unsigned long vm_start_gap(struct vm_area_struct *vma) ++{ ++ unsigned long vm_start = vma->vm_start; ++ ++ if (vma->vm_flags & VM_GROWSDOWN) { ++ vm_start -= stack_guard_gap; ++ if (vm_start > vma->vm_start) ++ vm_start = 0; ++ } ++ return vm_start; ++} ++ ++static inline unsigned long vm_end_gap(struct vm_area_struct *vma) ++{ ++ unsigned long vm_end = vma->vm_end; ++ ++ if (vma->vm_flags & VM_GROWSUP) { ++ vm_end += stack_guard_gap; ++ if (vm_end < vma->vm_end) ++ vm_end = -PAGE_SIZE; ++ } ++ return vm_end; ++} ++ + static inline unsigned long vma_pages(struct vm_area_struct *vma) + { + return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; +diff --git a/mm/memory.c b/mm/memory.c +index 3a3f316..06bbba9 100644 +--- a/mm/memory.c ++++ b/mm/memory.c +@@ -1654,12 +1654,6 @@ no_page_table: + return page; + } + +-static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr) +-{ +- return stack_guard_page_start(vma, addr) || +- stack_guard_page_end(vma, addr+PAGE_SIZE); +-} +- + /** + * __get_user_pages() - pin user pages in memory + * @tsk: task_struct of target task +@@ -1827,11 +1821,6 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, + int ret; + unsigned int fault_flags = 0; + +- /* For mlock, just skip the stack guard page. */ +- if (foll_flags & FOLL_MLOCK) { +- if (stack_guard_page(vma, start)) +- goto next_page; +- } + if (foll_flags & FOLL_WRITE) + fault_flags |= FAULT_FLAG_WRITE; + if (nonblocking) +@@ -3186,40 +3175,6 @@ out_release: + } + + /* +- * This is like a special single-page "expand_{down|up}wards()", +- * except we must first make sure that 'address{-|+}PAGE_SIZE' +- * doesn't hit another vma. +- */ +-static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address) +-{ +- address &= PAGE_MASK; +- if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) { +- struct vm_area_struct *prev = vma->vm_prev; +- +- /* +- * Is there a mapping abutting this one below? +- * +- * That's only ok if it's the same stack mapping +- * that has gotten split.. +- */ +- if (prev && prev->vm_end == address) +- return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM; +- +- expand_downwards(vma, address - PAGE_SIZE); +- } +- if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) { +- struct vm_area_struct *next = vma->vm_next; +- +- /* As VM_GROWSDOWN but s/below/above/ */ +- if (next && next->vm_start == address + PAGE_SIZE) +- return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM; +- +- expand_upwards(vma, address + PAGE_SIZE); +- } +- return 0; +-} +- +-/* + * We enter with non-exclusive mmap_sem (to exclude vma changes, + * but allow concurrent faults), and pte mapped but not yet locked. + * We return with mmap_sem still held, but pte unmapped and unlocked. +@@ -3234,10 +3189,6 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, + + pte_unmap(page_table); + +- /* Check if we need to add a guard page to the stack */ +- if (check_stack_guard_page(vma, address) < 0) +- return VM_FAULT_SIGBUS; +- + /* Use the zero-page for reads */ + if (!(flags & FAULT_FLAG_WRITE)) { + entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), +diff --git a/mm/mmap.c b/mm/mmap.c +index 8f87b14..cbdac38 100644 +--- a/mm/mmap.c ++++ b/mm/mmap.c +@@ -263,6 +263,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk) + unsigned long rlim, retval; + unsigned long newbrk, oldbrk; + struct mm_struct *mm = current->mm; ++ struct vm_area_struct *next; + unsigned long min_brk; + bool populate; + +@@ -308,7 +309,8 @@ 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. */ +@@ -331,10 +333,22 @@ 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; +@@ -418,7 +432,7 @@ void validate_mm(struct mm_struct *mm) + list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) + anon_vma_interval_tree_verify(avc); + vma_unlock_anon_vma(vma); +- highest_address = vma->vm_end; ++ highest_address = vm_end_gap(vma); + vma = vma->vm_next; + i++; + } +@@ -586,7 +600,7 @@ 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 +@@ -835,7 +849,7 @@ 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); + } +@@ -878,7 +892,7 @@ again: remove_next = 1 + (end > next->vm_end); + else if (next) + vma_gap_update(next); + else +- mm->highest_vm_end = end; ++ WARN_ON(mm->highest_vm_end != vm_end_gap(vma)); + } + if (insert && file) + uprobe_mmap(insert); +@@ -1670,7 +1684,7 @@ 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, +@@ -1681,7 +1695,7 @@ 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) +@@ -1708,8 +1722,8 @@ 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; + } + } +@@ -1773,7 +1787,7 @@ 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, +@@ -1786,7 +1800,7 @@ 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) +@@ -1812,7 +1826,7 @@ 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; + } + } +@@ -1850,7 +1864,7 @@ 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) +@@ -1861,9 +1875,10 @@ 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; + } + +@@ -1895,7 +1910,7 @@ 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; +@@ -1910,9 +1925,10 @@ 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; + } + +@@ -2104,32 +2120,40 @@ 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) + { +- int error; ++ struct vm_area_struct *next; ++ unsigned long gap_addr; ++ int error = 0; + + if (!(vma->vm_flags & VM_GROWSUP)) + return -EFAULT; + +- /* +- * We must make sure the anon_vma is allocated +- * so that the anon_vma locking is not a noop. +- */ ++ /* Guard against wrapping around to address 0. */ ++ address &= PAGE_MASK; ++ address += PAGE_SIZE; ++ if (!address) ++ return -ENOMEM; ++ ++ /* Enforce stack_guard_gap */ ++ gap_addr = address + stack_guard_gap; ++ if (gap_addr < address) ++ return -ENOMEM; ++ next = vma->vm_next; ++ if (next && next->vm_start < gap_addr) { ++ 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))) + return -ENOMEM; +- vma_lock_anon_vma(vma); + + /* + * vma->vm_start/vm_end cannot change under us because the caller + * is required to hold the mmap_sem in read mode. We need the + * anon_vma lock to serialize against concurrent expand_stacks. +- * Also guard against wrapping around to address 0. + */ +- if (address < PAGE_ALIGN(address+4)) +- address = PAGE_ALIGN(address+4); +- else { +- vma_unlock_anon_vma(vma); +- return -ENOMEM; +- } +- error = 0; ++ vma_lock_anon_vma(vma); + + /* Somebody else might have raced and expanded it already */ + if (address > vma->vm_end) { +@@ -2160,7 +2184,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address) + if (vma->vm_next) + vma_gap_update(vma->vm_next); + else +- vma->vm_mm->highest_vm_end = address; ++ vma->vm_mm->highest_vm_end = vm_end_gap(vma); + spin_unlock(&vma->vm_mm->page_table_lock); + + perf_event_mmap(vma); +@@ -2180,27 +2204,36 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address) + int expand_downwards(struct vm_area_struct *vma, + unsigned long address) + { ++ struct vm_area_struct *prev; ++ unsigned long gap_addr; + int error; + +- /* +- * We must make sure the anon_vma is allocated +- * so that the anon_vma locking is not a noop. +- */ +- if (unlikely(anon_vma_prepare(vma))) +- return -ENOMEM; +- + address &= PAGE_MASK; + error = security_mmap_addr(address); + if (error) + return error; + +- vma_lock_anon_vma(vma); ++ /* 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) { ++ 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; + + /* + * vma->vm_start/vm_end cannot change under us because the caller + * is required to hold the mmap_sem in read mode. We need the + * anon_vma lock to serialize against concurrent expand_stacks. + */ ++ vma_lock_anon_vma(vma); + + /* Somebody else might have raced and expanded it already */ + if (address < vma->vm_start) { +@@ -2242,28 +2275,25 @@ 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); + } + +@@ -2285,14 +2315,6 @@ 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); + } + +@@ -2389,7 +2411,7 @@ 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; + if (mm->unmap_area == arch_unmap_area) + addr = prev ? prev->vm_end : mm->mmap_base; +-- +2.1.4 + |