linux-kernel - [PATCH pidfd] signal: Add missing __user annotation to copy_siginfo_from_user

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Date:   Mon,  7 Dec 2020 01:02:52 +0100
From:   Jann Horn <jannh@...gle.com>
To:     Christian Brauner <christian.brauner@...ntu.com>
Cc:     Oleg Nesterov <oleg@...hat.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH pidfd] signal: Add missing __user annotation to copy_siginfo_from_user_any

copy_siginfo_from_user_any() takes a userspace pointer as second
argument; annotate the parameter type accordingly.

Signed-off-by: Jann Horn <jannh@...gle.com>
---
I'm messing around with clang's version of __user annotation checking
and it spotted this issue:

kernel/signal.c:3759:44: warning: casting to dereferenceable pointer removes 'noderef' attribute [-Wnoderef]
                ret = copy_siginfo_from_user_any(&kinfo, info);
                                                         ^~~~
Untracked cast to function pointer at kernel/signal.c:4294:26


Christian, since this is pidfd code, can you take this through your tree?
Or should I send this to akpm (or someone else)?

 kernel/signal.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index ef8f2a28d37c..4693191dc17c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3685,7 +3685,8 @@ static bool access_pidfd_pidns(struct pid *pid)
 	return true;
 }
 
-static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo, siginfo_t *info)
+static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo,
+		siginfo_t __user *info)
 {
 #ifdef CONFIG_COMPAT
 	/*

base-commit: 0477e92881850d44910a7e94fc2c46f96faa131f
-- 
2.29.2.576.ga3fc446d84-goog