2021-09-13 11:05:21

by Dongliang Mu

Subject: [PATCH] bpf: fix kmalloc bug in bpf_check

Since 7661809d493b ("mm: don't allow oversized kvmalloc() calls
") does not allow oversized kvmalloc, it triggers a kmalloc bug warning
at bpf_check.

Fix it by adding a sanity check in th check_btf_line.

Reported-by: [email protected]
Fixes: 7661809d493b ("mm: don't allow oversized kvmalloc() calls")
Signed-off-by: Dongliang Mu <[email protected]>
---
kernel/bpf/verifier.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 047ac4b4703b..3c5a79f78bc5 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9913,6 +9913,9 @@ static int check_btf_line(struct bpf_verifier_env *env,
if (!nr_linfo)
return 0;

+ if (nr_linfo > INT_MAX/sizeof(struct bpf_line_info))
+ return -EINVAL;
+
rec_size = attr->line_info_rec_size;
if (rec_size < MIN_BPF_LINEINFO_SIZE ||
rec_size > MAX_LINEINFO_REC_SIZE ||
--
2.25.1

2021-09-13 15:37:43

by Yonghong Song

Subject: Re: [PATCH] bpf: fix kmalloc bug in bpf_check

On 9/13/21 4:02 AM, Dongliang Mu wrote:
> Since 7661809d493b ("mm: don't allow oversized kvmalloc() calls
> ") does not allow oversized kvmalloc, it triggers a kmalloc bug warning
> at bpf_check.
>
> Fix it by adding a sanity check in th check_btf_line.
>
> Reported-by: [email protected]
> Fixes: 7661809d493b ("mm: don't allow oversized kvmalloc() calls")
> Signed-off-by: Dongliang Mu <[email protected]>

Thanks for the fix. A similar patch has been proposed here:
https://lore.kernel.org/bpf/[email protected]/

> ---
> kernel/bpf/verifier.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 047ac4b4703b..3c5a79f78bc5 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -9913,6 +9913,9 @@ static int check_btf_line(struct bpf_verifier_env *env,
> if (!nr_linfo)
> return 0;
>
> + if (nr_linfo > INT_MAX/sizeof(struct bpf_line_info))
> + return -EINVAL;
> +
> rec_size = attr->line_info_rec_size;
> if (rec_size < MIN_BPF_LINEINFO_SIZE ||
> rec_size > MAX_LINEINFO_REC_SIZE ||
>

2021-09-13 15:51:46

by Dongliang Mu

Subject: Re: [PATCH] bpf: fix kmalloc bug in bpf_check

On Mon, Sep 13, 2021 at 11:34 PM Yonghong Song <[email protected]> wrote:
>
>
>
> On 9/13/21 4:02 AM, Dongliang Mu wrote:
> > Since 7661809d493b ("mm: don't allow oversized kvmalloc() calls
> > ") does not allow oversized kvmalloc, it triggers a kmalloc bug warning
> > at bpf_check.
> >
> > Fix it by adding a sanity check in th check_btf_line.
> >
> > Reported-by: [email protected]
> > Fixes: 7661809d493b ("mm: don't allow oversized kvmalloc() calls")
> > Signed-off-by: Dongliang Mu <[email protected]>
>
> Thanks for the fix. A similar patch has been proposed here:
> https://lore.kernel.org/bpf/[email protected]/

OK, I see. Let's ignore this patch.

>
> > ---
> > kernel/bpf/verifier.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > index 047ac4b4703b..3c5a79f78bc5 100644
> > --- a/kernel/bpf/verifier.c
> > +++ b/kernel/bpf/verifier.c
> > @@ -9913,6 +9913,9 @@ static int check_btf_line(struct bpf_verifier_env *env,
> > if (!nr_linfo)
> > return 0;
> >
> > + if (nr_linfo > INT_MAX/sizeof(struct bpf_line_info))
> > + return -EINVAL;
> > +
> > rec_size = attr->line_info_rec_size;
> > if (rec_size < MIN_BPF_LINEINFO_SIZE ||
> > rec_size > MAX_LINEINFO_REC_SIZE ||
> >