2023-07-19 11:30:26

by Menglong Dong

Subject: [PATCH bpf-next] bpf, x86: initialize the variable "first_off" in save_args()

From: Menglong Dong <[email protected]>

As Dan Carpenter reported, the variable "first_off" which is passed to
clean_stack_garbage() in save_args() can be uninitialized, which can
cause runtime warnings with KMEMsan. Therefore, init it with 0.

Fixes: 473e3150e30a ("bpf, x86: allow function arguments up to 12 for TRACING")
Cc: Hao Peng <[email protected]>
Reported-by: Dan Carpenter <[email protected]>
Closes: https://lore.kernel.org/bpf/[email protected]/
Signed-off-by: Menglong Dong <[email protected]>
---
arch/x86/net/bpf_jit_comp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 5ab531be56ac..83c4b45dc65f 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1925,7 +1925,7 @@ static int get_nr_used_regs(const struct btf_func_model *m)
static void save_args(const struct btf_func_model *m, u8 **prog,
int stack_size, bool for_call_origin)
{
- int arg_regs, first_off, nr_regs = 0, nr_stack_slots = 0;
+ int arg_regs, first_off = 0, nr_regs = 0, nr_stack_slots = 0;
int i, j;

/* Store function arguments to stack.
--
2.40.1

2023-07-19 17:09:05

by patchwork-bot+netdevbpf

Subject: Re: [PATCH bpf-next] bpf, x86: initialize the variable "first_off" in save_args()

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <[email protected]>:

On Wed, 19 Jul 2023 19:03:30 +0800 you wrote:
> From: Menglong Dong <[email protected]>
>
> As Dan Carpenter reported, the variable "first_off" which is passed to
> clean_stack_garbage() in save_args() can be uninitialized, which can
> cause runtime warnings with KMEMsan. Therefore, init it with 0.
>
> Fixes: 473e3150e30a ("bpf, x86: allow function arguments up to 12 for TRACING")
> Cc: Hao Peng <[email protected]>
> Reported-by: Dan Carpenter <[email protected]>
> Closes: https://lore.kernel.org/bpf/[email protected]/
> Signed-off-by: Menglong Dong <[email protected]>
>
> [...]

Here is the summary with links:
- [bpf-next] bpf, x86: initialize the variable "first_off" in save_args()
https://git.kernel.org/bpf/bpf-next/c/492e797fdab2

You are awesome, thank you!
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