Check that size would not overflow before calculation (and return -EOVERFLOW if it will), to prevent potential out-of-bounds write with the following copy_from_user. Use kvmalloc_array in copy_user_syms to prevent out-of-bounds write into syms (and especially buf) as well.
Fixes: 0dcac272540613d4 ("bpf: Add multi kprobe link") Cc: stable@vger.kernel.org # 5.18 Signed-off-by: Eugene Syromiatnikov esyr@redhat.com --- kernel/trace/bpf_trace.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 7141ca8..9c041be 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2261,11 +2261,11 @@ static int copy_user_syms(struct user_syms *us, unsigned long __user *usyms, u32 int err = -ENOMEM; unsigned int i;
- syms = kvmalloc(cnt * sizeof(*syms), GFP_KERNEL); + syms = kvmalloc_array(cnt, sizeof(*syms), GFP_KERNEL); if (!syms) goto error;
- buf = kvmalloc(cnt * KSYM_NAME_LEN, GFP_KERNEL); + buf = kvmalloc_array(cnt, KSYM_NAME_LEN, GFP_KERNEL); if (!buf) goto error;
@@ -2461,7 +2461,8 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr if (!cnt) return -EINVAL;
- size = cnt * sizeof(*addrs); + if (check_mul_overflow(cnt, (u32)sizeof(*addrs), &size)) + return -EOVERFLOW; addrs = kvmalloc(size, GFP_KERNEL); if (!addrs) return -ENOMEM;