bpf: ensure all memory is initialized in bpf_get_current_comm

bpf: ensure all memory is initialized in bpf_get_current_comm

[Barret Rhoden]

BPF helpers that take an ARG_PTR_TO_UNINIT_MEM must ensure that all of
the memory is set, including beyond the end of the string.

Signed-off-by: Barret Rhoden <brho@google.com>
---
 kernel/bpf/helpers.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 5b278a38ae58..adffb2f87e44 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -257,7 +257,7 @@ BPF_CALL_2(bpf_get_current_comm, char *, buf, u32, size)
 		goto err_clear;
 
 	/* Verifier guarantees that size > 0 */
-	strscpy(buf, task->comm, size);
+	strscpy_pad(buf, task->comm, size);
 	return 0;
 err_clear:
 	memset(buf, 0, size);
-- 
2.40.0.348.gf938b09366-goog

Re: bpf: ensure all memory is initialized in bpf_get_current_comm

[Alexei Starovoitov]

On Wed, Apr 5, 2023 at 3:53 PM Barret Rhoden <brho@google.com> wrote:
>
> BPF helpers that take an ARG_PTR_TO_UNINIT_MEM must ensure that all of
> the memory is set, including beyond the end of the string.
>
> Signed-off-by: Barret Rhoden <brho@google.com>

The patch looks fine, but please rebase to bpf-next and resubmit
with [PATCH bpf-next] subj, so it goes through BPF CI.

See Documentation/bpf/bpf_devel_QA.rst

[PATCH bpf-next] bpf: ensure all memory is initialized in bpf_get_current_comm

[Barret Rhoden]

BPF helpers that take an ARG_PTR_TO_UNINIT_MEM must ensure that all of
the memory is set, including beyond the end of the string.

Signed-off-by: Barret Rhoden <brho@google.com>
---
 kernel/bpf/helpers.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 6be16db9f188..b6a5cda5bb59 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -258,7 +258,7 @@ BPF_CALL_2(bpf_get_current_comm, char *, buf, u32, size)
 		goto err_clear;
 
 	/* Verifier guarantees that size > 0 */
-	strscpy(buf, task->comm, size);
+	strscpy_pad(buf, task->comm, size);
 	return 0;
 err_clear:
 	memset(buf, 0, size);
-- 
2.40.0.577.gac1e443424-goog

Re: [PATCH bpf-next] bpf: ensure all memory is initialized in bpf_get_current_comm

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Thu,  6 Apr 2023 20:18:08 -0400 you wrote:
> BPF helpers that take an ARG_PTR_TO_UNINIT_MEM must ensure that all of
> the memory is set, including beyond the end of the string.
> 
> Signed-off-by: Barret Rhoden <brho@google.com>
> ---
>  kernel/bpf/helpers.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Here is the summary with links:
  - [bpf-next] bpf: ensure all memory is initialized in bpf_get_current_comm
    https://git.kernel.org/bpf/bpf-next/c/f3f213497797

You are awesome, thank you!
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