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Date: Thu, 20 Jan 2022 06:55:43 +0300 From: Dan Carpenter <dan.carpenter@...cle.com> To: Kees Cook <keescook@...omium.org> Cc: Jiasheng Jiang <jiasheng@...as.ac.cn>, arnd@...db.de, gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v2] lkdtm/bugs: Check for the NULL pointer after calling kmalloc On Wed, Jan 19, 2022 at 10:45:33AM -0800, Kees Cook wrote: > > diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c > > index f4cb94a9aa9c..c35ea54824ac 100644 > > --- a/drivers/misc/lkdtm/bugs.c > > +++ b/drivers/misc/lkdtm/bugs.c > > @@ -325,6 +325,11 @@ void lkdtm_ARRAY_BOUNDS(void) > > > > not_checked = kmalloc(sizeof(*not_checked) * 2, GFP_KERNEL); > > checked = kmalloc(sizeof(*checked) * 2, GFP_KERNEL); > > + if (!not_checked || !checked) { > > + kfree(not_checked); > > + kfree(checked); > > + return; > > + } > > This should explicitly yell about the memory failure. See the other > error cases for examples. I'd expect something like this before the > return: > > pr_err("FAIL: could not allocate required buffers\n"); Adding error messages for kmalloc failures is a checkpatch violation. Those allocations will never fail. There is already a warning message and stack trace built into kmalloc(). It's just a waste of resources to add the warning message. regards, dan carpenter
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