Messages in this thread | | | Date | Wed, 19 Jan 2022 10:45:33 -0800 | From | Kees Cook <> | Subject | Re: [PATCH v2] lkdtm/bugs: Check for the NULL pointer after calling kmalloc |
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On Wed, Jan 19, 2022 at 08:20:55PM +0800, Jiasheng Jiang wrote: > As the possible failure of the kmalloc(), the not_checked and checked > could be NULL pointer. > Therefore, it should be better to check it in order to avoid the > dereference of the NULL pointer. > Also, we need to kfree the 'not_checked' and 'checked' to avoid > the memory leak if fails. > And since it is just a test, it may directly return without error > number. > > Fixes: ae2e1aad3e48 ("drivers/misc/lkdtm/bugs.c: add arithmetic overflow and array bounds checks") > Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn> > --- > Changelog > > v1 -> v2 > > * Change 1. Add the kfree if fails. > --- > drivers/misc/lkdtm/bugs.c | 5 +++++ > 1 file changed, 5 insertions(+) > > 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");
-Kees
> > pr_info("Array access within bounds ...\n"); > /* For both, touch all bytes in the actual member size. */ > -- > 2.25.1 >
-- Kees Cook
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