3.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
commit e0d407564b532d978b03ceccebd224a05d02f111 upstream.
Unfortunately, I never committed the fix to a nasty oops which can
occur as a result of that commit:
------------[ cut here ]------------
kernel BUG at /home/olof/work/batch/include/linux/mm.h:414!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 0 PID: 490 Comm: killall5 Not tainted 3.11.0-rc3-00288-gabe0308 #53
task: e90acac0 ti: e9be8000 task.ti: e9be8000
PC is at special_mapping_fault+0xa4/0xc4
LR is at __do_fault+0x68/0x48c
This doesn't show up unless you do quite a bit of testing; a simple
boot test does not do this, so all my nightly tests were passing fine.
The reason for this is that install_special_mapping() expects the
page array to stick around, and as this was only inserting one page
which was stored on the kernel stack, that's why this was blowing up.
Reported-by: Olof Johansson <olof@xxxxxxxxx>
Tested-by: Olof Johansson <olof@xxxxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/kernel/process.c | 9 +++++----
arch/arm/kernel/signal.c | 41 +++++++++++++++++++----------------------
2 files changed, 24 insertions(+), 26 deletions(-)
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -478,17 +478,18 @@ const char *arch_vma_name(struct vm_area
"[sigpage]" : NULL;
}
+static struct page *signal_page;
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 page *page;
unsigned long addr;
int ret;
- page = get_signal_page();
- if (!page)
+ if (!signal_page)
+ signal_page = get_signal_page();
+ if (!signal_page)
return -ENOMEM;
down_write(&mm->mmap_sem);
@@ -500,7 +501,7 @@ int arch_setup_additional_pages(struct l
ret = install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
- &page);
+ &signal_page);
if (ret == 0)
mm->context.sigpage = addr;
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -609,35 +609,32 @@ do_work_pending(struct pt_regs *regs, un
return 0;
}
-static struct page *signal_page;
-
struct page *get_signal_page(void)
{
- if (!signal_page) {
- unsigned long ptr;
- unsigned offset;
- void *addr;
+ unsigned long ptr;
+ unsigned offset;
+ struct page *page;
+ void *addr;
- signal_page = alloc_pages(GFP_KERNEL, 0);
+ page = alloc_pages(GFP_KERNEL, 0);
- if (!signal_page)
- return NULL;
+ if (!page)
+ return NULL;
- addr = page_address(signal_page);
+ addr = page_address(page);
- /* Give the signal return code some randomness */
- offset = 0x200 + (get_random_int() & 0x7fc);
- signal_return_offset = offset;
+ /* Give the signal return code some randomness */
+ offset = 0x200 + (get_random_int() & 0x7fc);
+ signal_return_offset = offset;
- /*
- * Copy signal return handlers into the vector page, and
- * set sigreturn to be a pointer to these.
- */
- memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
+ /*
+ * Copy signal return handlers into the vector page, and
+ * set sigreturn to be a pointer to these.
+ */
+ memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
- ptr = (unsigned long)addr + offset;
- flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));
- }
+ ptr = (unsigned long)addr + offset;
+ flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));
- return signal_page;
+ return page;
}
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