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Message-ID: <20100820204355.GB14579@kroah.com>
Date: Fri, 20 Aug 2010 13:43:55 -0700
From: Greg KH <gregkh@...e.de>
To: linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
torvalds@...ux-foundation.org, stable@...nel.org, lwn@....net
Subject: Re: Linux 2.6.27.52
diff --git a/Makefile b/Makefile
index 5382c55..948de60 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
VERSION = 2
PATCHLEVEL = 6
SUBLEVEL = 27
-EXTRAVERSION = .51
+EXTRAVERSION = .52
NAME = Trembling Tortoise
# *DOCUMENTATION*
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 3384255..9d3c576 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -589,6 +589,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
unsigned long address;
int write, si_code;
int fault;
+ int should_exit_no_context = 0;
#ifdef CONFIG_X86_64
unsigned long flags;
#endif
@@ -876,6 +877,9 @@ no_context:
oops_end(flags, regs, SIGKILL);
#endif
+ if (should_exit_no_context)
+ return;
+
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
@@ -901,8 +905,11 @@ do_sigbus:
up_read(&mm->mmap_sem);
/* Kernel mode? Handle exceptions or die */
- if (!(error_code & PF_USER))
+ if (!(error_code & PF_USER)) {
+ should_exit_no_context = 1;
goto no_context;
+ }
+
#ifdef CONFIG_X86_32
/* User space => ok to do another page fault */
if (is_prefetch(regs, address, error_code))
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index d8be92a..0325100 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -205,6 +205,7 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
struct file *file = vma->vm_file;
int flags = vma->vm_flags;
unsigned long ino = 0;
+ unsigned long start;
dev_t dev = 0;
int len;
@@ -214,8 +215,13 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
ino = inode->i_ino;
}
+ /* We don't show the stack guard page in /proc/maps */
+ start = vma->vm_start;
+ if (vma->vm_flags & VM_GROWSDOWN)
+ start += PAGE_SIZE;
+
seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
- vma->vm_start,
+ start,
vma->vm_end,
flags & VM_READ ? 'r' : '-',
flags & VM_WRITE ? 'w' : '-',
diff --git a/mm/memory.c b/mm/memory.c
index 1300b70f..f0282eb 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2396,6 +2396,26 @@ out_nomap:
}
/*
+ * This is like a special single-page "expand_downwards()",
+ * except we must first make sure that 'address-PAGE_SIZE'
+ * doesn't hit another vma.
+ *
+ * The "find_vma()" will do the right thing even if we wrap
+ */
+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) {
+ address -= PAGE_SIZE;
+ if (find_vma(vma->vm_mm, address) != vma)
+ return -ENOMEM;
+
+ expand_stack(vma, address);
+ }
+ 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.
@@ -2408,9 +2428,13 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
spinlock_t *ptl;
pte_t entry;
- /* Allocate our own private page. */
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;
+
+ /* Allocate our own private page. */
if (unlikely(anon_vma_prepare(vma)))
goto oom;
page = alloc_zeroed_user_highpage_movable(vma, address);
diff --git a/mm/mmap.c b/mm/mmap.c
index f3e5bfe..08a32cf 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1573,7 +1573,7 @@ static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, un
* Overcommit.. This must be the final test, as it will
* update security statistics.
*/
- if (security_vm_enough_memory(grow))
+ if (security_vm_enough_memory_mm(mm, grow))
return -ENOMEM;
/* Ok, everything looks good - let it rip */
--
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