On Wed, Jan 04, 2017 at 12:45:32PM +0100, Greg KH wrote: > On Wed, Jan 04, 2017 at 11:37:49AM +0000, Robin Murphy wrote: > > When borrowing the pfn_valid() check from mmap_kmem(), somebody managed > > "sombody"? :) > > > to get physical and virtual addresses spectacularly muddled up, such > > that we've ended up with checks for one being the other. Whilst this > > does indeed prevent out-of-bounds accesses crashing, on most systems it > > also prevents the more desirable use-case of working at all ever. > > > > Check the *virtual* offset correctly for what it is. > > > > Reported-by: Jason A. Donenfeld <[email protected]> > > CC: [email protected] > > Fixes: 148a1bc84398 ("drivers: char: mem: Check {read,write}_kmem() > > addresses") > > Signed-off-by: Robin Murphy <[email protected]> > > --- > > drivers/char/mem.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/char/mem.c b/drivers/char/mem.c > > index 5bb1985ec484..bdc6a4018604 100644 > > --- a/drivers/char/mem.c > > +++ b/drivers/char/mem.c > > @@ -381,7 +381,7 @@ static ssize_t read_kmem(struct file *file, char __user > > *buf, > > char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */ > > int err = 0; > > > > - if (!pfn_valid(PFN_DOWN(p))) > > + if (!virt_addr_valid(p)) > > return -EIO; > > > > read = 0; > > @@ -512,7 +512,7 @@ static ssize_t write_kmem(struct file *file, const char > > __user *buf, > > char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ > > int err = 0; > > > > - if (!pfn_valid(PFN_DOWN(p))) > > + if (!virt_addr_valid(p)) > > return -EIO; > > > > if (p < (unsigned long) high_memory) { > > Jason, can you verify this fixes your test case?
Well, it fails kbuild testing, so can you try it again? thanks, greg k-h
