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@xxxxxxxxxxxxxxx> # 5.18
Signed-off-by: Eugene Syromiatnikov <esyr@xxxxxxxxxx>
---
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;
--
2.1.4
