* [PATCH 9/9] bpf: make bpf_check_uarg_tail_zero() use check_zeroed_user()
[not found] <20200528234025.GT23230@ZenIV.linux.org.uk>
@ 2020-05-29 23:28 ` Al Viro
2020-05-31 16:35 ` Alexei Starovoitov
0 siblings, 1 reply; 2+ messages in thread
From: Al Viro @ 2020-05-29 23:28 UTC (permalink / raw)
To: Linus Torvalds; +Cc: linux-kernel, linux-fsdevel, Alexei Starovoitov, bpf
From: Al Viro <viro@zeniv.linux.org.uk>
... rather than open-coding it, and badly, at that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
kernel/bpf/syscall.c | 25 ++++++-------------------
1 file changed, 6 insertions(+), 19 deletions(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 64783da34202..41ba746ecbc2 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -67,32 +67,19 @@ int bpf_check_uarg_tail_zero(void __user *uaddr,
size_t expected_size,
size_t actual_size)
{
- unsigned char __user *addr;
- unsigned char __user *end;
- unsigned char val;
- int err;
+ unsigned char __user *addr = uaddr + expected_size;
+ int res;
if (unlikely(actual_size > PAGE_SIZE)) /* silly large */
return -E2BIG;
- if (unlikely(!access_ok(uaddr, actual_size)))
- return -EFAULT;
-
if (actual_size <= expected_size)
return 0;
- addr = uaddr + expected_size;
- end = uaddr + actual_size;
-
- for (; addr < end; addr++) {
- err = get_user(val, addr);
- if (err)
- return err;
- if (val)
- return -E2BIG;
- }
-
- return 0;
+ res = check_zeroed_user(addr, actual_size - expected_size);
+ if (res < 0)
+ return res;
+ return res ? 0 : -E2BIG;
}
const struct bpf_map_ops bpf_map_offload_ops = {
--
2.11.0
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