For compat processes, userspace pointer size is different. Since the
copied array is iterated anyway, the simplest fix seems to be copy the
user-supplied array as-is and the iterate as an array of native or
compat pointers, depending on the in_compat_syscall() value.
Fixes: 0dcac272540613d4 ("bpf: Add multi kprobe link")
Signed-off-by: Eugene Syromiatnikov <[email protected]>
---
kernel/trace/bpf_trace.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index bf5bcfb..268c92b 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2353,16 +2353,19 @@ kprobe_multi_resolve_syms(const void __user *usyms, u32 cnt,
unsigned long *addrs)
{
unsigned long addr, sym_size;
- u32 size;
+ u32 size, elem_size;
const char __user **syms;
+ compat_uptr_t __user *compat_syms;
int err = -ENOMEM;
unsigned int i;
char *func;
- if (check_mul_overflow(cnt, (u32)sizeof(*syms), &size))
+ elem_size = in_compat_syscall() ? sizeof(*compat_syms) : sizeof(*syms);
+ if (check_mul_overflow(cnt, elem_size, &size))
return -EOVERFLOW;
- size = cnt * sizeof(*syms);
+ size = cnt * elem_size;
syms = kvzalloc(size, GFP_KERNEL);
+ compat_syms = (void *)syms;
if (!syms)
return -ENOMEM;
@@ -2376,7 +2379,10 @@ kprobe_multi_resolve_syms(const void __user *usyms, u32 cnt,
}
for (i = 0; i < cnt; i++) {
- err = strncpy_from_user(func, syms[i], KSYM_NAME_LEN);
+ const char __user *ufunc = in_compat_syscall()
+ ? (char __user *)(uintptr_t)compat_syms[i]
+ : syms[i];
+ err = strncpy_from_user(func, ufunc, KSYM_NAME_LEN);
if (err == KSYM_NAME_LEN)
err = -E2BIG;
if (err < 0)
--
2.1.4