Messages in this thread | | | Date | Tue, 17 May 2022 00:08:28 -0700 | Subject | Re: [PATCH bpf v2 2/4] bpf_trace: support 32-bit kernels in bpf_kprobe_multi_link_attach | From | Yonghong Song <> |
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On 5/16/22 4:05 PM, Eugene Syromiatnikov wrote: > It seems that there is no reason not to support 32-bit architectures; > doing so requires a bit of rework with respect to cookies handling, > however, as the current code implicitly assumes > that sizeof(long) == sizeof(u64). > > Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com> > --- > kernel/trace/bpf_trace.c | 18 +++++++++--------- > 1 file changed, 9 insertions(+), 9 deletions(-) > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index f1d4e68..bf5bcfb 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -2406,16 +2406,12 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr > struct bpf_link_primer link_primer; > void __user *ucookies; > unsigned long *addrs; > - u32 flags, cnt, size; > + u32 flags, cnt, size, cookies_size; > void __user *uaddrs; > u64 *cookies = NULL; > void __user *usyms; > int err; > > - /* no support for 32bit archs yet */ > - if (sizeof(u64) != sizeof(void *)) > - return -EOPNOTSUPP; > - > if (prog->expected_attach_type != BPF_TRACE_KPROBE_MULTI) > return -EINVAL; > > @@ -2425,6 +2421,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr > > uaddrs = u64_to_user_ptr(attr->link_create.kprobe_multi.addrs); > usyms = u64_to_user_ptr(attr->link_create.kprobe_multi.syms); > + ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies); > if (!!uaddrs == !!usyms) > return -EINVAL; > > @@ -2432,8 +2429,11 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr > if (!cnt) > return -EINVAL; > > - if (check_mul_overflow(cnt, (u32)sizeof(*addrs), &size)) > + if (check_mul_overflow(cnt, (u32)sizeof(*addrs), &size) || > + (ucookies && > + check_mul_overflow(cnt, (u32)sizeof(*cookies), &cookies_size))) { > return -EOVERFLOW; > + } > size = cnt * sizeof(*addrs);
size has been calculated, no need to calculate again.
> addrs = kvmalloc(size, GFP_KERNEL); > if (!addrs) > @@ -2450,14 +2450,14 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr > goto error; > } > > - ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies); > if (ucookies) { > - cookies = kvmalloc(size, GFP_KERNEL); > + cookies_size = cnt * sizeof(*cookies);
same for cookies_size.
> + cookies = kvmalloc(cookies_size, GFP_KERNEL); > if (!cookies) { > err = -ENOMEM; > goto error; > } > - if (copy_from_user(cookies, ucookies, size)) { > + if (copy_from_user(cookies, ucookies, cookies_size)) { > err = -EFAULT; > goto error; > }
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