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. Add the same check
to kprobe_multi_resolve_syms in case it will be called from elsewhere
in the future.
Fixes: 0dcac272540613d4 ("bpf: Add multi kprobe link")
Signed-off-by: Eugene Syromiatnikov <esyr@xxxxxxxxxx>
---
kernel/trace/bpf_trace.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index d8553f4..e90c4ce7 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2358,6 +2358,8 @@ kprobe_multi_resolve_syms(const void __user *usyms, u32 cnt,
unsigned int i;
char *func;
+ if (check_mul_overflow(cnt, sizeof(*syms), &size))
+ return -EOVERFLOW;
size = cnt * sizeof(*syms);
syms = kvzalloc(size, GFP_KERNEL);
if (!syms)
@@ -2429,6 +2431,8 @@ 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))
+ return -EOVERFLOW;
size = cnt * sizeof(*addrs);
addrs = kvmalloc(size, GFP_KERNEL);
if (!addrs)
--
2.1.4
