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? thanks, greg k-h
