Messages in this thread Patch in this message | | | Date | Sat, 30 Jan 2010 17:25:10 +0800 | From | Wu Fengguang <> | Subject | [PATCH 1/4] hwpoison: prevent /dev/kmem from accessing hwpoison pages |
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When /dev/kmem read()/write() encounters hwpoison page, stop it and return the amount of work done till now, or return -EIO if nothing have been copied.
For simplicity, hwpoison pages accessed by vmalloc address are siliently skipped, instead of returning -EIO.
CC: Greg KH <greg@kroah.com> CC: Andi Kleen <andi@firstfloor.org> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> CC: Christoph Lameter <cl@linux-foundation.org> CC: Ingo Molnar <mingo@elte.hu> CC: Tejun Heo <tj@kernel.org> CC: Nick Piggin <npiggin@suse.de> CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> --- drivers/char/mem.c | 18 ++++++++++++++---- mm/vmalloc.c | 4 ++-- 2 files changed, 16 insertions(+), 6 deletions(-)
--- linux-mm.orig/drivers/char/mem.c 2010-01-30 17:14:12.000000000 +0800 +++ linux-mm/drivers/char/mem.c 2010-01-30 17:20:18.000000000 +0800 @@ -426,6 +426,9 @@ static ssize_t read_kmem(struct file *fi */ kbuf = xlate_dev_kmem_ptr((char *)p); + if (unlikely(virt_addr_valid(kbuf) && + PageHWPoison(virt_to_page(kbuf)))) + return -EIO; if (copy_to_user(buf, kbuf, sz)) return -EFAULT; buf += sz; @@ -471,6 +474,7 @@ do_write_kmem(unsigned long p, const cha { ssize_t written, sz; unsigned long copied; + int err = 0; written = 0; #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED @@ -497,13 +501,19 @@ do_write_kmem(unsigned long p, const cha */ ptr = xlate_dev_kmem_ptr((char *)p); + if (unlikely(virt_addr_valid(ptr) && + PageHWPoison(virt_to_page(ptr)))) { + err = -EIO; + break; + } + copied = copy_from_user(ptr, buf, sz); if (copied) { written += sz - copied; - if (written) - break; - return -EFAULT; + err = -EFAULT; + break; } + buf += sz; p += sz; count -= sz; @@ -511,7 +521,7 @@ do_write_kmem(unsigned long p, const cha } *ppos += written; - return written; + return written ? written : err; } --- linux-mm.orig/mm/vmalloc.c 2010-01-30 17:14:15.000000000 +0800 +++ linux-mm/mm/vmalloc.c 2010-01-30 17:20:18.000000000 +0800 @@ -1669,7 +1669,7 @@ static int aligned_vread(char *buf, char * interface, rarely used. Instead of that, we'll use * kmap() and get small overhead in this access function. */ - if (p) { + if (p && !PageHWPoison(p)) { /* * we can expect USER0 is not used (see vread/vwrite's * function description) @@ -1708,7 +1708,7 @@ static int aligned_vwrite(char *buf, cha * interface, rarely used. Instead of that, we'll use * kmap() and get small overhead in this access function. */ - if (p) { + if (p && !PageHWPoison(p)) { /* * we can expect USER0 is not used (see vread/vwrite's * function description)
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