On Mon, 22 Nov 2010 20:11:03 +0300 Vasiliy Kulikov <segoon@xxxxxxxxxxxx> wrote: > count is not checked before kmalloc() call. Too big value would > generate stack dump. To prevent this limit 'count' maximum value. > 1024 looks OK - the data should be the string of tens of bytes. > > Signed-off-by: Vasiliy Kulikov <segoon@xxxxxxxxxxxx> > --- > Compile tested only. > > v1 had incorrect comment text, as Dan Rosenberg noticed. > > drivers/gpu/vga/vgaarb.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c > index c380c65..09e3090 100644 > --- a/drivers/gpu/vga/vgaarb.c > +++ b/drivers/gpu/vga/vgaarb.c > @@ -836,6 +836,8 @@ static ssize_t vga_arb_write(struct file *file, const char __user * buf, > int ret_val; > int i; > > + if (count > 1024) > + count = 1024; > > kbuf = kmalloc(count + 1, GFP_KERNEL); > if (!kbuf) Bit ugly, that. Arguably we should just let the allocation attempt pass through to kmalloc() and let kmalloc() return an error if it was too large. Possibly we need a __GFP_NOWARN in there somewhere. Please send us that stack dump? The code should be using strndup_user() anyway. And perhaps strndup_user() needs __GFP_NOWARN treatment. -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
